英文 - 考试分类 - 正風學習中心

Why are earthquakes so difficult to predict?

1. Polymath Simple English Definition: A person who knows a lot about many different things. Sentence in Video: &quot;In one three, Two, Chinese polymath Zhang Heng presented theHan court with his latest invention.&quot;2. Skeptical Simple English Definition: Not easily believing that something is true. Sentence in Video: &quot;The court was somewhat skeptical, Especially when the devicetriggered on a seemingly quiet afternoon.&quot;3. Anticipate Simple English Definition: To guess or expect that something will happen. Sentence in Video: &quot;So why are earthquakes so hard to anticipate?&quot;4. Jagged Simple English Definition: Having sharp, rough edges that are not smooth or even. Sentence in Video: &quot;Earth&#39;s crust is made from several vast, Jagged slabs of rockcalled tectonic plates.&quot;5. Molten Simple English Definition: Turned into liquid by being heated very much. Sentence in Video: &quot;Each riding on a hot, Partially molten layer of earth&#39;s mantle.&quot;6. Minuscule Simple English Definition: Extremely small. Sentence in Video: &quot;It&#39;s hard enough to monitor these minuscule movements.&quot;7. Varied Simple English Definition: Different from each other; not all the same. Sentence in Video: &quot;But the factors that turn shifts into seismic events are far morevaried.&quot;8. Friction Simple English Definition: The force that stops two things from moving easily whenthey are touching. Sentence in Video: &quot;Diverse rocks also react differently to friction and high temperatures.&quot;9. Lubricating Simple English Definition: Making something able to move more easily by reducingfriction. Sentence in Video: &quot;Some partially melt, And can release lubricating fluids made ofsuperheated minerals.&quot;10. Prone Simple English Definition: Likely to have a particular problem or experience aparticular thing. Sentence in Video: &quot;But some are left dry, prone to dangerous buildups ofpressure.&quot;11. Cyclical Simple English Definition: Happening in a regular pattern that repeats over time. Sentence in Video: &quot;Because some of these forces occur at largely constant rates,The behavior of the plates is somewhat cyclical today.&quot;12. Forecasting Simple English Definition: Saying what will probably happen in the future, based oninformation available now. Sentence in Video: &quot;Many of our most reliable clues come from long termforecasting, Related to when and where earthquakes have previously occurred atthe scale of millennia.&quot;13. Overdue Simple English Definition: Not having happened when expected or needed. Sentence in Video: &quot;This allows us to make predictions about when highly activefaults, Like the San Andreas, are overdue for a massive earthquake.&quot;14. Timeframes Simple English Definition: A period of time during which something is expected tohappen. Sentence in Video: &quot;But due to the many variables involved, This method can onlypredict very loose timeframes.&quot;15. Imminent Simple English Definition: Going to happen very soon. Sentence in Video: &quot;To predict more imminent events, Researchers haveinvestigated the vibrations earth elicits before a quake.&quot;16. Elicits  Simple English Definition: Causes something to be expressed or produced. Sentence in Video: &quot;To predict more imminent events, Researchers haveinvestigated the vibrations earth elicits before a quake.&quot;17. Rigorous Simple English Definition: Done in a very careful, thorough, and detailed way. Sentence in Video: &quot;Which can use a rigorous blend of geological data to identifyregions at risk.&quot;18. Concentrations Simple English Definition: The amount of a particular substance in a certain place orvolume. Sentence in Video: &quot;Nearby researchers recorded surprisingly high concentrations ofthe radioactive isotope pair, Radon and Thoron.&quot;19. Promising Simple English Definition: Showing signs of being successful or good in the future. Sentence in Video: &quot;It could become a promising warning system, Potentiallypredicting quakes a week in advance.&quot;20. Respond Simple English Definition: To act in answer to a situation or event. Sentence in Video: &quot;But for now, These technologies can help us prepare andrespond quickly to areas in need.&quot;

2025-12-25 困难

How tall can a tree grow?

1. Sequoias English Definition: A type of very large evergreen tree native to California, knownfor being some of the tallest and oldest trees in the world. Sentence in Video: &quot;Californian sequoias tower over earth&#39;s other estimated sixtythousand tree species.&quot;2. Behemoths English Definition: Very large or powerful things, especially living creatures. Sentence in Video: &quot;But even these behemoths seem to have their limits.&quot;3. Sap English Definition: A liquid that flows inside plants, carrying nutrients and sugars. Sentence in Video: &quot;It all comes down to sap.&quot;4. Photosynthesis English Definition: The process by which green plants use sunlight to make foodfrom carbon dioxide and water. Sentence in Video: &quot;They need to bring sugars obtained from photosynthesis andnutrients brought in through the root system to wherever growth is happening.&quot;5. Phloem English Definition: A type of plant tissue that transports sugars and other organicnutrients from the leaves to other parts of the plant. Sentence in Video: &quot;Floem sap is thick like honey and flows down the plant&#39;s phloemtissue to distribute sugar throughout the tree.&quot;（注：視頻中 &quot;flo em&quot; 為 &quot;phloem&quot;的口語化連讀，標準拼寫為 phloem）6. Xylem English Definition: A type of plant tissue that transports water and dissolvedminerals from the roots up to the leaves and other parts of the plant. Sentence in Video: &quot;Right beside the phloem is the tree&#39;s other tissue type, thexylem.&quot;7. Ions English Definition: Atoms or groups of atoms that have an electric charge, formedby gaining or losing electrons. Sentence in Video: &quot;This tissue is packed with nutrients and ions like calcium, potassium and iron.&quot;8. Osmotic movement English Definition: The movement of water molecules through a semipermeablemembrane from an area of lower solute concentration to an area of higher soluteconcentration, to balance the concentration on both sides. Sentence in Video: &quot;This process called osmotic movement creates nutrient richxylem sap.&quot;9. Formidable English Definition: Difficult to deal with or overcome; impressive in a way thatcauses fear or respect. Sentence in Video: &quot;But this journey faces a formidable obstacle: Gravity.&quot;10. Herculean English Definition: Requiring great strength, effort, or courage; extremely difficult. Sentence in Video: &quot;To accomplish this herculean task, the xylem relies on threeforces.&quot;11. Transpiration English Definition: The process by which water is lost from a plant&#39;s leaves as watervapor, mainly through small pores called stomata. Sentence in Video: &quot;This evaporation called transpiration creates negative pressurein the xylem, pulling watery xylem sap up the tree.&quot;12. Capillary action English Definition: The ability of a liquid to flow in narrow spaces without theassistance of, or even against, external forces like gravity, due to adhesive andcohesive forces. Sentence in Video: &quot;This pull is aided by a fundamental property of water calledcapillary action.&quot;13. Adhesive forces English Definition: The forces of attraction between molecules of differentsubstances, such as water molecules and the walls of a narrow tube. Sentence in Video: &quot;The attraction between water molecules and the adhesiveforces between the water and its environment can beat out gravity.&quot;14. Dwindle English Definition: To become smaller or less in amount, number, or strength. Sentence in Video: &quot;As trees grow taller and taller, the supply of these vital fluidsbegins to dwindle.&quot;15. Hydraulic limitation hypothesis  English Definition: A scientific idea that suggests the height of trees is limited bytheir ability to transport water (and the nutrients in it) from the roots to the top,due to the increasing difficulty of overcoming gravity as height increases. Sentence in Video: &quot;This model, known as the hydraulic limitation hypothesis, iscurrently our best explanation for why trees have limited heights.&quot;16. Canopy English Definition: The upper layer of branches and leaves in a forest, formed by thetops of trees. Sentence in Video: &quot;Find out in this video about one scientist&#39;s bold exploration ofthe canopy of an ancient redwood.&quot;17. Stomata English Definition: Small pores on the surface of a plant&#39;s leaves (and sometimesstems) that allow for gas exchange (taking in carbon dioxide and releasing oxygen)and transpiration. Sentence in Video: &quot;As part of photosynthesis, leaves open and close pores calledstomata.&quot;18. Nutrients English Definition: Substances that plants and animals need to live, grow, and stayhealthy, such as vitamins, minerals, and sugars. Sentence in Video: &quot;They need to bring sugars obtained from photosynthesis andnutrients brought in through the root system to wherever growth is happening.&quot;19. Evaporates English Definition: To change from a liquid state to a gas or vapor state, especiallydue to heating (like sunlight warming water in leaves). Sentence in Video: &quot;But they also create an opening through which waterevaporates.&quot;20. Hypothesis English Definition: A proposed explanation for a phenomenon, based on limitedevidence, that is used as a starting point for further investigation. Sentence in Video: &quot;This model, known as the hydraulic limitation hypothesis, iscurrently our best explanation for why trees have limited heights.&quot;

2025-12-25 困难

Dog History

1. Canis lupus (n.) English Definition: The scientific name for the gray wolf, a large canine native toEurasia and North America. Sentence in Context: Today, wherever you find Homo sapiens on Earth, you&#39;re likelyto find another species nearby—Canis lupus (either in its wild form or domesticatedas dogs).2. Homo sapiens (n.) English Definition: The scientific name for modern humans, the only survivingspecies of the genus Homo. Sentence in Context: Homo sapiens have built homes and communities on Earth forover 200,000 years, often accompanied by domesticated dogs.3. Paleolithic (adj.) English Definition: Relating to the early period of human history, characterized bythe use of stone tools and hunting-gathering lifestyles. Sentence in Context: When our Paleolithic ancestors first settled in Eurasia about100,000 years ago, gray wolves were one of their main rivals at the top of the foodchain.4. Predator (n.) English Definition: An animal that hunts, kills, and eats other animals for food. Sentence in Context: Gray wolves are fearsome predators—they can exert over 300pounds of pressure with a single bite to crush bones.5. Forage (v.) English Definition: To search for food or provisions, especially in the wild. Sentence in Context: Less aggressive wolves could get close to human campsto forage on leftovers, which helped them survive.6. Tame (adj./v.) English Definition: (adj.) Not dangerous or frightened of humans; domesticated. (v.)To train an animal to be obedient and not afraid of humans. Sentence in Context: Over time, the genetic traits of these more tame wolves werepassed on, gradually breeding tamed wolves near human settlements.7. Canine (n./adj.) English Definition: (n.) A dog or related animal (such as a wolf or fox) belonging to the Canidae family. (adj.) Relating to dogs or the Canidae family. Sentence in Context: Canine species like wolves and dogs share similar socialstructures, which helps them integrate into human families easily.8. Domestication (n.) English Definition: The process of adapting wild plants or animals for human use,such as farming or companionship. Sentence in Context: The domestication of wolves into dogs is one of the earliestexamples of human-controlled evolution, starting about 33,000 years ago.9. Ancestor (n.) English Definition: A person or animal from whom one is descended; a forefather orforebear. Sentence in Context: Modern dogs&#39; ancestors are gray wolves—though theirappearances have changed greatly through selective breeding.10. Congenital (adj.) English Definition: (Of a disease or physical abnormality) present from birth. Sentence in Context: Many aesthetic traits in purebred dogs are accompaniedby congenital health issues, such as breathing difficulties or spinal injuries.11. Neoteny (n.) English Definition: The retention of juvenile features in an adult organism, oftenseen in domesticated animals. Sentence in Context: The preference for docile, playful traits in dogs ledto neoteny—adult dogs still keep many youthful characteristics like large eyes andplayful behavior.12. Oxytocin (n.) English Definition: A hormone produced in the brain that is associated with feelingsof love, bonding, and trust. Sentence in Context: When dogs and humans interact, both of their bodiesrelease oxytocin, which strengthens their emotional bond.13. Eurasia (n.) English Definition: The combined continental landmass of Europe and Asia. Sentence in Context: Gray wolves were originally native to Eurasia, where they firstencountered and interacted with Paleolithic humans.14. Selective breeding (n.) English Definition: The process of choosing specific animals or plants to breed, inorder to pass on desired traits to the next generation. Sentence in Context: All dog breeds are the result of selective breeding—humans have chosen dogs with certain traits (like herding or guarding skills) to reproduce.15. Subspecies (n.) English Definition: A taxonomic category that ranks below species, representing adistinct population within a species. Sentence in Context: Domestic dogs are considered a subspecies of Canis lupus, asthey share most genetic traits with gray wolves.16. Social structure (n.) English Definition: The organization of a group of animals (or humans) into ahierarchy or system of relationships. Sentence in Context: Wolves and humans both have complex socialstructures—they live and hunt in groups made up of several core families.17. Sentry (n.) English Definition: A person or animal that guards a place and alerts others todanger. Sentence in Context: Early domesticated wolves acted as sentries for human camps,warning people of approaching enemies.18. Herd (v./n.) English Definition: (v.) To gather, guide, or control a group of animals (such as cowsor sheep). (n.) A group of animals of the same species that live or move together. Sentence in Context: Stocky dogs with short legs were bred to herd livestock, usingtheir bodies to guide the herd in the right direction.19. Evolution (n.) English Definition: The process by which species change over generations throughgenetic variation and natural selection (or artificial selection in domesticated cases). Sentence in Context: The evolution of wolves into dogs is a classic example ofartificial selection—humans, not nature, drove the change in traits.20. Fossil record (n.) English Definition: The collection of fossils (remains or traces of ancient organisms)that provide evidence of past life and evolutionary history. Sentence in Context: The fossil record shows that the earliest primitive dogs (orwolf-dogs) appeared about 33,000 years ago, with smaller bodies and shorter snoutsthan wolves.

2025-12-25 困难

Can you escape nuclear contamination?

1. Nuclear Fission Definition: The process in which the nucleus of an atom splits into two or moresmaller nuclei, releasing a large amount of energy. Sentence: The destructive power of nuclear weapons comes from nuclear fission,where the nucleus splits and releases incredible energy.2. Chain Reaction Definition: A series of reactions where the product of one reaction triggers the nextreaction, continuing the process. Sentence: In some materials, neutrons from one fission are absorbed by nearbyatoms, creating a chain reaction that generates explosive yields.3. Explosive Yield Definition: The amount of energy released by an explosive, usually measured inunits like tons of TNT. Sentence: Let’s consider an explosion with an explosive yield equal to 10,000 tonsof TNT, which can destroy several city blocks.4. Fireball Definition: A large, bright ball of fire produced by a powerful explosion, especially anuclear explosion. Sentence: An explosion like this creates a fireball that is capable of destroyingseveral city blocks instantly.5. Shock Wave Definition: A strong wave of pressure that moves outward from an explosion,causing damage to objects in its path. Sentence: The shock wave from the nuclear explosion can damage buildings severalkilometers away.6. Ionizing Radiation Definition: High-energy radiation that can remove electrons from atoms ormolecules, potentially causing cell damage. Sentence: The sand-sized particles from nuclear fallout emit ionizing radiation thatcan separate electrons from molecules and atoms.7. Radioactive Fallout Definition: The radioactive particles that fall from the atmosphere to the ground after a nuclear explosion. Sentence: Dangerous concentrations of radioactive fallout can be carried by upperatmospheric winds to areas tens of kilometers downwind.8. Radioactive Particles Definition: Tiny pieces of matter that emit radiation due to unstable atomic nuclei. Sentence: When the fireball cools, unstable atoms from nuclear fission mix withdebris to form radioactive particles.9. Cellular Damage Definition: Harm to the structure or function of cells, often caused by radiation ortoxic substances. Sentence: Exposure to large amounts of ionizing radiation can lead to cellulardamage, radiation burns, and even death.10. Radiation Burns Definition: Burns on the skin or other tissues caused by exposure to high levels ofradiation. Sentence: People exposed to excessive ionizing radiation may suffer from radiationburns in addition to more serious health issues.11. Radiation Sickness Definition: An illness caused by excessive exposure to ionizing radiation, withsymptoms like nausea, fatigue, and organ failure. Sentence: Severe exposure to radioactive fallout can result in radiation sickness,which may be life-threatening if not treated.12. Sheltering (Noun) Definition: The act of seeking and staying in a safe place to protect oneself fromdanger, such as radiation or explosions. Sentence: Sheltering in a strong building is the best way to protect yourself duringand after a nuclear explosion.13. Reinforced Building Definition: A building made stronger with materials like steel or extra concrete towithstand damage from disasters. Sentence: Within the shock wave’s range, reinforced buildings should be able towithstand the pressure from the nuclear explosion.14. Basement (as a Shelter) Definition: The underground floor of a building, used here as a safe place to avoidradiation or explosions. Sentence: After finding a reinforced building, staying in the basement provides better protection against heat and flying debris.15. Debris Definition: Scattered pieces of broken material or rubbish, especially from a disasterlike an explosion. Sentence: If the fireball is close to the Earth, it will pull thousands of tons of dirtand debris into the atmosphere.16. Unstable Atoms Definition: Atoms with an unbalanced number of protons and neutrons, which emitradiation to become more stable. Sentence: Nuclear fission produces unstable atoms that mix with debris to form themost dangerous long-term effect of nuclear explosions.17. Downwind Definition: In the direction that the wind is blowing; an area located where windcarries substances (like fallout). Sentence: Upper atmospheric winds can carry radioactive falloutto downwind areas, creating dangerous radiation levels there.18. First Responders Definition: People who arrive first at the scene of a disaster to provide help, such asfirefighters, police, or medical workers. Sentence: It’s best to stay in the shelter and follow updates from first responders toknow the safest route forward.19. Protocol Definition: A set of formal rules or procedures to follow in a specific situation,especially for safety or emergencies. Sentence: For those in and beyond the shock wave range, scientificallysupported protocols may save lives after a nuclear explosion.20. Catastrophic Event Definition: A sudden, very serious event that causes great damage, loss of life, ordisaster. Definition: We hope no one will ever experience such a catastrophic event as anuclear explosion again.

2025-12-25 困难

World History of Cats

1. Battleship English Definition: A large warship with thick armor and large-caliber guns, designedfor naval battles. Sentence in Video: &quot;The german battleship bismarck sank in a fierce firefight.&quot;2. Firefight English Definition: A battle involving the exchange of gunfire between opposingmilitary forces. Sentence in Video: &quot;The german battleship bismarck sank in a fierce firefight.&quot;3. Crew English Definition: The group of people who work on and operate a ship, aircraft, orother vehicle. Sentence in Video: &quot;Leaving only one hundred and eighteen of her two thousandtwo hundred crew members alive.&quot;4. Destroyer English Definition: A fast, maneuverable warship designed to protect larger shipsfrom enemy attacks, especially submarines and aircraft. Sentence in Video: &quot;But when a british destroyer came to collect the prisoners.&quot;5. Survivor English Definition: A person (or animal) who continues to live after an accident, war,illness, or other dangerous or life-threatening event. Sentence in Video: &quot;They found an unexpected survivor.&quot;6. Cling English Definition: To hold on tightly to something, especially to avoid falling. Sentence in Video: &quot;A black and white cat clinging to a floating plank.&quot;7. Plank English Definition: A long, flat piece of wood or other material, often used inconstruction or as a floating object. Sentence in Video: &quot;A black and white cat clinging to a floating plank.&quot;8. Morale English Definition: The level of confidence, enthusiasm, and discipline of a person or group, especially in a work or military setting. Sentence in Video: &quot;This cat hunted rats and raised british morale.&quot;9. Torpedo English Definition: A self-propelled underwater missile designed to explode when ithits a ship or submarine. Sentence in Video: &quot;Until a sudden torpedo strike shattered the hull and sank theship.&quot;10. Hull English Definition: The main body of a ship or boat, excluding the masts, sails, andsuperstructure. Sentence in Video: &quot;Until a sudden torpedo strike shattered the hull and sank theship.&quot;11. Domestication English Definition: The process of taming wild animals or plants and adapting themfor human use or companionship. Sentence in Video: &quot;The domestication of the modern house cat can be traced backto more than ten thousand years ago.&quot;12. Fertile Crescent English Definition: A region in the Middle East, including parts of modern-day Iraq,Syria, Lebanon, Israel, and Jordan, known for its fertile land and role in thedevelopment of early agriculture. Sentence in Video: &quot;In the fertile crescent at the start of the neolithic era.&quot;13. Neolithic English Definition: Relating to the later part of the Stone Age, when humans beganpracticing agriculture and domesticating animals. Sentence in Video: &quot;In the fertile crescent at the start of the neolithic era.&quot;14. Silos English Definition: Tall, cylindrical structures used for storing grain or other bulkmaterials. Sentence in Video: &quot;These neolithic farmers stored their excess grain in large pitsand short clay silos.&quot;15. Rodents English Definition: Small mammals with sharp front teeth that grow continuously,such as rats, mice, and squirrels, which often infest food stores. Sentence in Video: &quot;But these stores of food attracted hordes of rodents.&quot; 16. Carnivorous English Definition: Feeding on meat; a carnivorous animal eats other animals. Sentence in Video: &quot;These wildcats were fast, fierce carnivorous hunters.&quot;17. Scourge English Definition: A person or thing that causes great trouble or suffering; a plague. Sentence in Video: &quot;And the mediterranean vermin were a major scourge of theseven seas.&quot;18. Provisions English Definition: Food, drink, and other supplies needed for a journey, expedition,or period of time away from home. Sentence in Video: &quot;They ate provisions and gnawed at lines of rope.&quot;19. Venomous English Definition: Producing venom (a poisonous substance) that is injected intoprey or enemies, usually through a bite or sting. Sentence in Video: &quot;Revered for their ability to dispatch venomous snakes.&quot;20. Genomes English Definition: The complete set of genes or genetic material present in a cell ororganism. Sentence in Video: &quot;But close analysis of the genomes and coat patterns of moderncats tells us that...&quot;

2025-12-25 困难

How do roller coasters affect our bodies?

1. Thrilling (adj.) Definition: Causing excitement and pleasure because of being unusual or dangerous. Sentence: The thrilling loops of the early roller coasters often led to serious neckinjuries.2. Whiplash (n.) Definition: An injury to the neck caused by a sudden sharp movement, especially ina car accident or on a roller coaster. Sentence: The Flip Flap Railway, America’s first looping roller coaster, caused manysevere whiplashes.3. Ejection (n.) Definition: The act of being forced out of a place or a vehicle suddenly and violently. Sentence: Early roller coasters had risks of ejection, as their safety designs were notmature.4. Gravitational (adj.) Definition: Relating to the force that attracts objects towards each other, especiallythe force that makes things fall to the ground. Sentence: Every roller coaster design centers on gravitational energy and itsinteraction with the ride.5. Potential Energy (n.) Definition: The energy that a substance or object has because of its position orcondition, rather than because it is moving. Sentence: Roller coasters build up potential energy as they climb the initial lift hill.6. Kinetic Energy (n.) Definition: The energy that a moving object has because of its motion. Sentence: When a roller coaster descends, it converts potential energy into kineticenergy to gain speed.7. G-force (n.) Definition: A unit used to measure the force of gravity on a person or object,especially when they are accelerating or decelerating. Sentence: Modern roller coasters are designed to keep G-forces around 5, which thehuman body can tolerate. 8. Traction (n.) Definition: The ability of a wheel, tire, or shoe to stick to a surface, preventingslipping. (Note: Implied in &quot;getting stuck&quot; in the video) Sentence: Early ride designers worried about roller coasters losing traction andgetting stuck on the track.9. Compensate (v.) Definition: To do something to reduce or correct a problem or weakness. Sentence: Early roller coaster builders overcompensated by pushing trains downhills hard and braking sharply at stations.10. Hypoxia (n.) Definition: A condition in which the body or a part of it does not receive enoughoxygen. Sentence: When blood flows away from the brain due to high G-forces, retinal cellssuffer from hypoxia, causing vision problems.11. Retina (n.) Definition: The layer at the back of the eye that receives light and sends signals tothe brain, allowing people to see. Sentence: Hypoxia in retina cells can damage their ability to process light, leading totemporary blindness.12. Crimson (adj.) Definition: Of a deep red color. Sentence: When riders are upside down, blood rushes to the skull, causing a crimsonvision called red out.13. Red Out (n.) Definition: A visual disturbance where the field of vision turns red, caused byincreased blood pressure in the head (common in roller coasters). Sentence: The &quot;red out&quot; phenomenon occurs when blood floods the skull duringupside-down roller coaster loops.14. Weightlessness (n.) Definition: The state of being without weight, especially in space or during free fall.(Paraphrased from &quot;short-term weightlessness&quot; in the video) Sentence: Short-term weightlessness on roller coasters is mostly harmless but cancause motion sickness.15. Motion Sickness (n.) Definition: A feeling of nausea, dizziness, or discomfort caused by being in a movingvehicle or ride.  Sentence: Weightlessness on roller coasters can lead to motion sickness bysuspending fluid in the inner ear.16. Harness (n.) Definition: A set of straps used to hold a person securely in place, especially on aride or in a vehicle. Sentence: Modern roller coasters use multiple belts and harnesses to prevent ridersfrom separating from seats.17. Constraints (n.) Definition: Things that limit or restrict what you can do. Sentence: Today’s extra constraints, like advanced harnesses, make roller coasterssafer than ever before.18. 3D Modeling (n.) Definition: The process of creating a three-dimensional digital representation of anobject or system using software. Sentence: 3D modeling helps roller coaster engineers test designs and ensure ridersafety before construction.19. Simulation Software (n.) Definition: Computer programs that create virtual scenarios to 模仿 real-lifeprocesses or events. Sentence: Simulation software allows engineers to predict how roller coasters willaffect the human body.20. Adrenaline (n.) Definition: A hormone released in the body when a person is frightened, angry, orexcited, making the heart beat faster and giving more energy. Sentence: The adrenaline rush from roller coasters is part of their appeal, eventhough it may cause dizziness for some.

2025-12-25 困难

What is Time ?

1. Measurements (n.) Definition: The act or process of measuring the size, amount, or degree ofsomething. Sentence in Video: &quot;The earliest time measurements were observations of cycles ofthe natural world.&quot;2. Cycles (n.) Definition: A series of events that repeat regularly in the same order. Sentence in Video: &quot;The earliest time measurements were observations of cycles ofthe natural world.&quot;3. Precise (adj.) Definition: Exact, accurate, and careful about details. Sentence in Video: &quot;More precise timekeeping like sundials and mechanical clockseventually came along.&quot;4. Mechanical (adj.) Definition: Relating to machines or the way machines work. Sentence in Video: &quot;More precise timekeeping like sundials and mechanical clockseventually came along.&quot;5. Physically (adv.) Definition: In a way that relates to the body or material things, not ideas or themind. Sentence in Video: &quot;Is time something that physically exists, or is it just in ourheads?&quot;6. Relativity (n.) Definition: A theory developed by Einstein that explains how space, time, andgravity work, especially for objects moving very fast. Sentence in Video: &quot;His theory of relativity tells us that time passes for everyone.&quot;7. Malleability (n.) Definition: The ability to be changed or shaped easily. Sentence in Video: &quot;Einstein resolved the malleability of time by combining it withspace.&quot; 8. Fabric (n.) Definition: The basic structure of something, especially a system or organization. Sentence in Video: &quot;Einstein&#39;s theory seemed to confirm that time is woven into thevery fabric of the universe.&quot;9. Arrow of time (n. phrase) Definition: The concept that time moves in only one direction (from past to future),not backwards. Sentence in Video: &quot;This is called the arrow of time.&quot;10. Thermodynamics (n.) Definition: The branch of physics that studies heat, energy, and how they affectmatter. Sentence in Video: &quot;This is described by the second law of thermodynamics.&quot;11. Entropy (n.) Definition: A measure of the disorder or randomness in a system; it always increasesover time in a closed system. Sentence in Video: &quot;Which says that systems will gain disorder or entropy overtime.&quot;12. Fundamental (adj.) Definition: Basic and important; forming the base of something. Sentence in Video: &quot;It should be in our most fundamental equations describing theuniverse.&quot;13. Equations (n.) Definition: Mathematical statements that show two amounts or values are equal,used to solve problems. Sentence in Video: &quot;We currently have two sets of equations that govern physics.&quot;14. Quantum (adj.) Definition: Relating to the smallest possible amount of energy or matter, asdescribed by quantum physics. Sentence in Video: &quot;General relativity describes the very large, while quantumphysics explains the very small.&quot;15. Reconciling (v.) Definition: Finding a way to make two different ideas, facts, or systems worktogether or agree. Sentence in Video: &quot;One of the biggest goals in physics has been reconciling the twointo one theory of everything.&quot; 16. Speculative (adj.) Definition: Based on guesses or ideas that have not been proven to be true. Sentence in Video: &quot;Like all current theories of everything, that equation isspeculative.&quot;17. Emergent (adj.) Definition: Describing a property that appears when parts of a system worktogether, but does not exist in the individual parts. Sentence in Video: &quot;Maybe it could exist as an emergent one.&quot;18. Perceive (v.) Definition: To notice or understand something using your senses or mind. Sentence in Video: &quot;Generated by the limitations of the way we perceive theuniverse.&quot;19. Fluid (adj.) Definition: Smooth and continuous, without sudden changes or breaks. Sentence in Video: &quot;That appear to have a fluid, continuous change between them.&quot;20. Sequence (n.) Definition: A particular order in which related things follow each other. Sentence in Video: &quot;Our brains perceive the passage of time from the sequence ofstill images.&quot;

2025-12-25 困难

What if concrete cracks can heal themselves?

1. Catastrophic (adj.) Definition: Causing sudden and very serious damage or suffering. Sentence: Concrete, though widely used, is prone to catastrophic cracking whichendangers building safety.2. Hydration (n.) Definition: The chemical reaction between a substance and water, especially when ithardens as a result. Sentence: When water is added to the concrete mixture, cement forms a paste andhardens quickly through hydration.3. Aggregate (n.) Definition: A collection of small particles, such as sand or stones, used in makingconcrete. Sentence: Concrete consists of rough stones, sand, and aggregate mixed withcement powder.4. Spores (n.) Definition: Tiny reproductive cells produced by some plants, bacteria, and fungi thatcan develop into new organisms. Sentence: Scientists add bacterial or fungal spores to concrete mixtures, whichremain dormant for centuries.5. Dormant (adj.) Definition: In a state of inactivity but capable of becoming active later. Sentence: The spores in concrete stay dormant until water enters through cracksand triggers their growth.6. Calcium Carbonate (n.) Definition: A white chemical compound found in limestone, chalk, and marble, oftenformed through chemical reactions. Sentence: The reaction between calcium hydroxide and carbon dioxide producescalcium carbonate crystals that fill concrete cracks.7. Calcium Hydroxide (n.) Definition: A white powder formed when calcium oxide reacts with water, used insome chemical processes.  Sentence: Water entering concrete cracks hydrates calcium oxide, forming calciumhydroxide that further reacts with carbon dioxide.8. Corrosion (n.) Definition: The process of metal being destroyed gradually by a chemical reactionwith substances like water and oxygen. Sentence: Small cracks in concrete let in water and oxygen, leading to the corrosionof steel reinforcements inside.9. Resilient (adj.) Definition: Able to withstand difficult conditions and quickly return to a normalstate. Sentence: Self-healing concrete with spores has greater potential to be moreresilient and durable than traditional concrete.10. Microorganisms (n.) Definition: Very small living things that can only be seen with a microscope, such asbacteria or fungi. Sentence: Hardworking microorganisms can fully repair cracks nearly one millimeterwide in concrete within three weeks.11. Viscous (adj.) Definition: Thick and sticky, not flowing easily. Sentence: When cracks form in concrete, fiber tubes break open and release viscousadhesive to seal the gaps.12. Autogenous Healing (n.) Definition: The natural process by which a material repairs its own small crackswithout external help. Sentence: Concrete has a limited autogenous healing ability—its calcium hydroxidereacts with CO₂ to form crack-filling crystals.13. Reinforcements (n.) Definition: Materials (usually steel bars) added to concrete to make it stronger andmore resistant to stress. Sentence: Concrete is often used as secondary support around steel reinforcementsin large structures like bridges.14. Durability (n.) Definition: The ability of a material to last a long time without being damaged orworn out. Sentence: Improving concrete’s self-healing ability can greatly enhance its durabilityand reduce repair costs. 15. Mitigate (v.) Definition: To make something less severe, harmful, or painful. Sentence: Adding hidden adhesives to concrete is one way to mitigate the problemof large cracks, though it has limitations.16. Porous (adj.) Definition: Having small holes that allow liquid or air to pass through. Sentence: If concrete becomes too porous, it is more likely to absorb water andspeed up the corrosion of internal steel.17. Formulation (n.) Definition: A specific mixture of ingredients used to make a product, especially achemical or industrial one. Sentence: Humans have used various cement formulations for over four thousandyears to meet different construction needs.18. Seep (v.) Definition: To flow slowly through small holes or gaps. Sentence: Water can seep into tiny concrete cracks, activating the dormant sporesinside the material.19. Retard (v.) Definition: To slow down the progress or development of something. Sentence: Poor concrete quality can retard the hydration process, making thematerial less strong and more prone to cracking.20. Infrastructure (n.) Definition: The basic systems and services that a country or organization needs tofunction properly, such as roads, bridges, and buildings. Sentence: Self-healing concrete could revolutionize infrastructure maintenance byreducing the need for frequent repairs.

2025-12-25 困难

How the next ice age will happen?

1. Ice Age（冰河時代） Simple Definition: A long period when Earth was much colder, with lots of ice onland. Sentence: Long ago, during an ice age, big ice fields covered parts of Europe andNorth America.2. Carbon Dioxide（二氧化碳） Simple Definition: A gas in the air; too much of it makes Earth warmer. Sentence: Burning oil or coal adds more carbon dioxide to the air, changing theclimate.3. Volcanic Activity（火山活動） Simple Definition: When volcanoes erupt, sending out gas, lava, or ash. Sentence: Volcanic activity is a natural thing that can change how much carbondioxide is in the air.4. Earth’s Orbit（地球軌道） Simple Definition: The path Earth follows when it goes around the Sun. Sentence: Changes in Earth’s orbit can make some places get more or less sunlighteach year.5. Summer Temperature（夏季溫度） Simple Definition: How hot or cool it is during summer. Sentence: If summer temperatures stay cool, snow from winter won’t melt, and icebuilds up over time.6. Ice Melt（冰層融化） Simple Definition: When big piles of ice turn into water. Sentence: When more sunlight hits ice fields, ice melt starts, and the ocean levels goup.7. Sea Levels（海平面） Simple Definition: The average height of the ocean’s surface. Sentence: After the last ice age, ice melt made sea levels rise by 130 meters.8. Fossil Fuels（化石燃料）  Simple Definition: Things like coal, oil, or gas we burn for energy; they come fromold plants and animals. Sentence: Using more fossil fuels in the past 200 years has made carbon dioxide inthe air go up.9. Global Temperature（全球溫度） Simple Definition: The average temperature of the whole Earth. Sentence: More carbon dioxide has made the global temperature go up by nearly 1degree Celsius.10. Ice Sheets（大冰原） Simple Definition: Huge, thick layers of ice covering large areas (like in Greenland orAntarctica). Sentence: Ice sheets reflect sunlight back into space, which makes Earth evencooler.11. Climate Records（氣候記錄） Simple Definition: Info from rocks, ice, or fossils that tells us what the climate waslike before. Sentence: Climate records show Earth usually gets cooler over thousands of years,but this stopped 150 years ago.12. Coastal Cities（沿海城市） Simple Definition: Cities that are next to the ocean. Sentence: If sea levels rise 30-100 centimeters, many coastal cities will haveproblems.13. Carbon Emissions（碳排放） Simple Definition: Carbon dioxide released into the air (usually from burning fuels). Sentence: Cutting carbon emissions now can help stop too much ice from melting.14. Antarctic Ice（南極冰） Simple Definition: The ice that covers the continent of Antarctica. Sentence: Scientists study bubbles in Antarctic ice to learn about old air and carbondioxide levels.15. Marine Fossils（海洋化石） Simple Definition: Old remains of ocean animals or plants (like shells turned torock). Sentence: Marine fossils help scientists know how hot or cold Earth was long ago.16. Polar Ice Caps（極地冰蓋）  Simple Definition: Big piles of ice at the North and South Poles. Sentence: Without polar ice caps, the ocean would be 70 meters higher than it isnow.17. Snowball Earth（雪球地球） Simple Definition: A time long ago when almost all of Earth was covered in ice. Sentence: About 700 million years ago, there was a Snowball Earth, with ice all overthe planet.18. Pollen Analysis（花粉分析） Simple Definition: Studying old pollen from plants to learn about past climate. Sentence: Pollen analysis helped scientists find that temperatures were highestabout 6,000 years ago.19. Atmospheric Air（大氣） Simple Definition: The air that surrounds Earth. Sentence: Changes in the atmospheric air’s carbon dioxide levels cause big climateshifts.20. Coastal Communities（沿海社區） Simple Definition: Groups of people living near the ocean (like small towns orvillages). Sentence: Stopping too much ice melt can help protect coastal communities fromrising seas.

2025-12-25 困难

Change your sleep time

1. Habitats (n.) Simple English Definition: The usual places where people or animals live. Sentence in Video: Here we see an early bird and a night owl in theirnatural habitats.2. Exhausted (adj.) Simple English Definition: Very tired, with no energy left. Sentence in Video: They slowly get more and more exhausted until finally crashingaround sunset.3. Stumbling (v.) Simple English Definition: Walking unsteadily, like you might fall. Sentence in Video: The night owl rises long after the sun, stumbling groggily fromtheir bed.4. Groggily (adv.) Simple English Definition: In a way that’s sleepy and not clear-headed. Sentence in Video: The night owl rises long after the sun, stumbling groggily fromtheir bed.5. Stride (n.) Simple English Definition: A good, steady pace where you feel active and capable. Sentence in Video: But they don&#39;t really hit their stride until later in the day.6. Coast (v.) Simple English Definition: Keep going easily without much effort. Sentence in Video: At which point they comfortably coast past sunset.7. Predetermined (adj.) Simple English Definition: Decided before something happens, not chosen later. Sentence in Video: Are our natural sleep schedules predetermined at birth?8. Extremes (n.) Simple English Definition: The two very different ends of a range (like &quot;very early&quot;and &quot;very late&quot; for sleep). Sentence in Video: There&#39;s a lot of space between these extremes. 9. Track (v.) Simple English Definition: Follow and keep an eye on something over time. Sentence in Video: These nerve cells respond to light exposure coming in throughyour eyes to track the day-night cycle.10. Steady (adj.) Simple English Definition: Regular and not changing much. Sentence in Video: That steady rhythm helps determine the body&#39;s flow ofhormones.11. Flow (n.) Simple English Definition: The way something moves or happens over time (here,how hormones work in the body). Sentence in Video: That steady rhythm helps determine the body&#39;s flow ofhormones.12. Predictions (n.) Simple English Definition: Guesses about what will happen in the future. Sentence in Video: The system can make predictions about when you&#39;re likely toneed sleep.13. Accordingly (adv.) Simple English Definition: In a way that matches what’s needed or expected. Sentence in Video: The system can make predictions about when you&#39;re likely toneed sleep and prepare your body accordingly.14. Strict (adj.) Simple English Definition: Not flexible, with clear rules you have to follow. Sentence in Video: Can we change it just by sticking to a strict schedule?15. Unique (adj.) Simple English Definition: Different from everyone or everything else. Sentence in Video: Everyone&#39;s bodies are unique.16. Shift (v.) Simple English Definition: Change over time. Sentence in Video: While these factors can shift with age.17. Cultivate (v.) Simple English Definition: Develop and keep (like habits). Sentence in Video: That said you can cultivate habits to help or hinder your circadian rhythm.18. Hinder (v.) Simple English Definition: Slow down or make something harder. Sentence in Video: That said you can cultivate habits to help or hinder yourcircadian rhythm.19. Unpredictable (adj.) Simple English Definition: Not easy to guess or plan for, because it changes a lot. Sentence in Video: Their unpredictable sleeping habits weaken their entirecircadian system.20. Sufficient (adj.) Simple English Definition: Enough for what you need. Sentence in Video: Getting sufficient contrast between bright daylight and dimmernighttime light is essential.

2025-12-25 困难

英文

考试列表 109

Why are earthquakes so difficult to predict?

How tall can a tree grow?

Dog History

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World History of Cats

How do roller coasters affect our bodies?

What is Time ?

What if concrete cracks can heal themselves?

How the next ice age will happen?

Change your sleep time