Quasars as Extreme Case of Galaxies

天体英语知识点总结高中一、IntroductionThe study of celestial bodies, or heavenly bodies, is known as astronomy. Astronomy is a natural science that involves the observation and analysis of celestial phenomena. It has been a subject of human fascination for millennia, with civilizations around the world creating myths, legends, and astronomical calendars associated with the movements of the sun, moon, and stars.In recent centuries, astronomy has developed into a field of scientific inquiry, using advanced tools and techniques to study the universe and its contents. This has led to many groundbreaking discoveries and a better understanding of the cosmos.In this article, we will explore some key concepts and terms related to astronomy and celestial bodies, providing a comprehensive overview of this fascinating field of study.二、The Solar SystemThe solar system is the collection of celestial bodies that orbit the sun, including planets, moons, asteroids, comets, and other objects. The sun is the central star of the solar system, providing light and heat to the planets and other bodies that orbit it.1. Planets: There are eight recognized planets in the solar system, including Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. These planets vary in size, composition, and distance from the sun, and each has its own unique characteristics.2. Moons: Moons are natural satellites that orbit planets. The most well-known example is Earth's moon, but many other planets in the solar system also have moons of their own. Some planets, such as Jupiter and Saturn, have a large number of moons, while others have only a few.3. Asteroids: Asteroids are small, rocky bodies that orbit the sun. They are found primarily in the asteroid belt, which lies between the orbits of Mars and Jupiter. Some asteroids have elliptical or irregular orbits that bring them close to the inner solar system, posing a potential threat to Earth and other planets.4. Comets: Comets are icy bodies that orbit the sun in highly elliptical orbits. When a comet approaches the sun, its ice begins to vaporize, creating a bright glowing tail that can be seen from Earth. Comets are thought to be remnants from the early solar system and provide valuable insights into its formation and evolution.5. Dwarf Planets: In addition to the eight recognized planets, there are also a number of dwarf planets in the solar system. These are celestial bodies that are similar to planets in some ways but do not meet all the criteria for being classified as planets. The best-known example is Pluto, which was reclassified as a dwarf planet in 2006.三、Stars and GalaxiesStars are massive, luminous spheres of plasma that emit light and heat through nuclear fusion. They are the building blocks of galaxies, which are vast collections of stars, gas, and dust held together by gravity.1. Star Formation: Stars form from the gravitational collapse of dense regions within interstellar clouds of gas and dust. As the cloud contracts, it heats up and eventually reaches a temperature and density at which nuclear fusion reactions can occur, turning hydrogen into helium and releasing large amounts of energy in the process.2. Stellar Evolution: Stars go through a life cycle that depends on their initial mass. Low-mass stars, such as our sun, spend most of their lives in a stable state, fusing hydrogen into helium in their cores. Eventually, they exhaust their nuclear fuel and expand into red giants before shedding their outer layers and becoming white dwarfs. High-mass stars, on the other hand, undergo more dramatic evolutionary stages, including supernova explosions and the formation of neutron stars or black holes.3. Galaxies: Galaxies come in a variety of shapes and sizes, from small irregular galaxies to giant elliptical and spiral galaxies. The Milky Way, the galaxy in which our solar system resides, is a spiral galaxy with several arms of stars and gas. Galaxies are thought to have formed from the gravitational collapse of large clouds of gas and dust in the early universe.4. The Universe: The universe is the vast expanse of space and time that contains all known matter and energy. It is believed to have originated from a single point in an event known as the Big Bang, which occurred approximately 13.8 billion years ago. The study of the universe, its origin, and its evolution is a fundamental aspect of astronomy, leading to many important discoveries and insights into the nature of the cosmos.四、Observational AstronomyObservational astronomy is the study of celestial objects and phenomena through direct observation using telescopes, cameras, and other instruments. This branch of astronomy plays a crucial role in advancing our understanding of the universe.1. Telescopes: Telescopes are the primary tools used by astronomers to observe celestial objects. They collect and magnify light from distant objects, allowing astronomers to study stars, planets, galaxies, and other phenomena in great detail. There are several types of telescopes, including optical telescopes that work by collecting visible light, as well as radio telescopes, X-ray telescopes, and other specialized instruments that capture non-visible forms of radiation.2. Astronomical Imaging: Astronomical imaging refers to the process of capturing and analyzing images of celestial objects. Modern digital cameras and imaging sensors have revolutionized this field, allowing astronomers to produce high-resolution images of distantgalaxies, planetary surfaces, and other astronomical features. Imaging data is often used to study the composition, structure, and evolution of celestial bodies.3. Spectroscopy: Spectroscopy is the study of the interaction between light and matter. By analyzing the spectrum of light emitted or absorbed by an object, astronomers can learn about its composition, temperature, and other important properties. Spectroscopy has been instrumental in advancing our knowledge of stars, galaxies, and the interstellar medium.4. Astronomical Surveys: Astronomical surveys are large-scale projects that aim to systematically observe and catalog objects in the sky. These surveys cover a wide range of wavelengths and are used to study the distribution of galaxies, the structure of the universe, and the properties of individual celestial objects. The data collected from these surveys is crucial for advancing our understanding of the cosmos.五、Astrophysics and CosmologyAstrophysics is the branch of astronomy that seeks to understand the physical properties and behavior of celestial objects and phenomena. It involves the application of principles from physics and other sciences to study the universe and its contents.1. Stellar Physics: Stellar physics focuses on the study of stars, including their structure, evolution, and energy production. It seeks to explain the processes that govern the behavior of stars, such as nuclear fusion in their cores, the generation of magnetic fields, and the formation of stellar remnants.2. Galactic and Extragalactic Astrophysics: This subfield of astrophysics deals with the study of galaxies and the large-scale structures of the universe. It explores the distribution of matter and energy, the formation of galaxies, and the dynamics of galactic clusters. It also addresses the properties of objects outside our galaxy, such as quasars, pulsars, and active galactic nuclei.3. Cosmology: Cosmology is the study of the origin, evolution, and ultimate fate of the universe. It seeks to understand the large-scale structure of the cosmos, the nature of dark matter and dark energy, and the cosmic microwave background radiation left over from the Big Bang. Cosmologists use principles from general relativity and particle physics to develop theoretical models of the universe and test them against observational data.4. Black Holes and Neutron Stars: Black holes and neutron stars are extreme objects that result from the gravitational collapse of massive stars. They have unique properties, such as intense gravitational fields and the emission of powerful radiation. The study of these objects is an important area of research in astrophysics, as they provide insights into the behavior of matter under extreme conditions.六、ConclusionAstronomy is a fascinating and dynamic field of study that encompasses a wide range of topics, from the study of stars and planets to the exploration of the universe on the largest scales. It offers a unique perspective on the nature of our existence and our place in the cosmos.The knowledge and insights gained from astronomy have practical applications in many areas, including space exploration, the development of new technologies, and the search for extraterrestrial life. As our understanding of the universe continues to expand, so too will the impact of astronomy on our lives and our understanding of the world around us.In conclusion, astronomy is a cornerstone of human curiosity and scientific endeavor, revealing the wonders of the universe and the beauty of the celestial realm. The study of celestial bodies continues to capture the imagination of people around the world and drive us to explore and understand the cosmos in ever-greater detail.。

跟宇宙有关的英语作文60字英文回答：The universe is a vast and mysterious place, full of wonders that we are only just beginning to understand. It is estimated to be around 13.8 billion years old, and contains billions of galaxies, each with billions of stars. The universe is constantly expanding, and scientists believe that it will eventually reach a state of maximum expansion, known as the Big Freeze.Some of the most fascinating objects in the universe include black holes, neutron stars, and quasars. Black holes are regions of spacetime with such intense gravity that nothing, not even light, can escape. Neutron stars are the collapsed cores of massive stars, and are incredibly dense. Quasars are extremely bright objects that are powered by the accretion of matter onto a supermassive black hole.The universe is also home to a wide variety of planets, moons, and asteroids. Our own solar system contains eight planets, including Earth, Mars, and Jupiter. There are also billions of other planets in the universe, some of which may be habitable.The study of the universe is known as astronomy, and it is one of the oldest sciences. Astronomers use telescopes and other instruments to observe the universe and learn more about its history and evolution.中文回答：宇宙是一个浩瀚而充满奥秘的地方，它充满了我们才刚刚开始理解的奇迹。

a rXiv:as tr o-ph/14180v11Apr21Astrophysical Ages and Time Scales ASP Conference Series,Vol.TBD,2001T.von Hippel,N.Manset,C.Simpson High Redshift Quasars and Star Formation History M.Dietrich and F.Hamann University of Florida,Department of Astronomy,211Bryant Space Science Center,Gainesville,FL 32611-2055,USA Abstract.Quasars are among the most luminous objects in the uni-verse,and they can be studied in detail up to the highest known redshift.Assuming that the gas associated with quasars is closely related to the interstellar medium of the host galaxy,quasars can be used as tracer of the star formation history in the early universe.We have observed a small sample of quasars at redshifts 3∼<z ∼<5and present results using NV/CIV and NV/HeII as well as MgII/FeII to estimate the date of the first major star formation epoch.These line ratios indicate solar and supersolar metallicities of the gas close to the quasars.Assuming times of τevol ≃1Gyr the first star formation epoch can be dated to z f ≃10,corresponding to an age of the universe of less than 5·108yrs (H o =65km s −1Mpc −1,ΩM =0.3,ΩΛ=0.7).1.Introduction In the context of cosmic evolution,the epoch of first star formation in the early universe is of fundamental importance.During the last few years,several galaxies (cf.,Dey et al.1998;Weymann et al.1998;Spinrad et al.1998;Chen et al.1999;van Breugel et al.1999;Hu et al.1999)and quasars (Fan et al.1999,2000a,2000b;Zheng et al.2000;Stern et al.2000)at redshifts of z ≥5have been detected.Because quasars are among the most luminous objects in the universe,they are valuable probes of conditions at early cosmic times.One particularly important diagnostic is their gas metallicity.If the gas near highredshift quasars is related to the interstellar matter of the young host galaxies,quasars can be used to probe the star formation and chemical enrichment history of those galactic environments.Recent studies of quasars at moderately high redshifts (z ∼>3)show solar and enhanced metallicities in the line emitting gas (cf.,Hamann &Ferland 1993;Osmer et al.1994;Ferland et al.1996;Hamann &Ferland 1999;Dietrich &Wilhelm-Erkens 2000).These results require a rapid and efficient phase of star formation in the early universe,e.g.in the dense galactic or proto-galactic nuclei where quasars reside.In the following,we present results of an ongoing study of quasars at red-shifts 3∼<z ∼<5.The emission line ratios of NV1240to CIV1549and HeII1640are used as well as MgII2798vs.FeII UV.The relative strength of these ratios indicates that the first epoch of star formation started at redshifts z ≥10.In current cosmological models,the age of the universe at those redshifts is less than 5·108yrs (H o =65km s −1Mpc −1,ΩM =0.3,ΩΛ=0.7;cf.,Carroll et al.1992).1High Redshift Quasars2 2.ObservationsThe observations of high redshift quasars were carried out at several observato-ries during1993and2000.We used telescopes at Calar Alto Observatory/Spain, McDonald Observatory/Texas,USA,La Silla Observatory/ESO,Chile,Paranal Observatory/ESO,Chile,Keck/Hawaii,USA,and CTIO/Chile(Tab.1).Table1.Observing log of the studied high redshift quasarsHigh Redshift Quasars32.1.The MethodQuasars show a prominent emission line spectrum which provides information on the physical conditions of the gas i.e.temperature,density,ionization state, and the chemical composition.Although the ratios of strong emission lines like Lyα1215to CIV1549are quite insensitive to the metallicity,other ratios can provide indirect constraints.The key to using emission line ratios to estimate the metallicity is the dif-ferent production rates of primary elements like carbon and secondary elements, like nitrogen.N is selectively enhanced by secondary processing at moderate to high metallicities,leading to N increasing as roughly Z2(cf.,Hamann&Ferland 1993;Vila-Costas&Edmunds1993).Recent model calculations provide evi-dence for a strong metallicity dependence of emission line ratios involving such elements.Hence,NV1240vs.CIV1549and NV1240vs.HeII1640are of partic-ular interest for determining the chemical composition of the gas(cf.,Hamann &Ferland1999for a review).The different time scales of the enrichment of gas with“α-elements”(e.g., O and Mg)and iron are another important aspect using emission line ratios to probe the star formation history.α-elements are produced predominantly in massive stars on short time scales.These elements are released from massive-star supernovae(Types II,Ib,Ic).The dominant source of iron is ascribed to intermediate mass stars in binary systems ending in supernova type Ia explosions (cf.,Wheeler et al.1989).The amount of iron returned to the interstellar medium in SN II ejecta is rather low(e.g.,Yoshii et al.1998).The significantly different time scales of the release ofα-elements and iron to the interstellar medium results in a time delay of the order of∼1Gyr.Detecting strong FeII emission at high redshift can be taken as an indication that the star formation of the stars which had released the iron had occurred∼1Gyr earlier.The viability of the FeII/MgII emission line ratio as an abundance indicator was discussed by Hamann&Ferland(1999).3.Results3.1.NV1240vs.CIV1549and HeII1640Line RatiosThe quasars observed in the optical wavelength range were used to determine the NV1240/CIV1549and NV1240/HeII1640emission line ratios.To measure the NV1240line strength we had to deblend the Lyα1215,NV1240emission line complex.We also deblended the CIV1549,HeII1640,OIII]1663emission line complex to measure HeII1640(cf.,Dietrich&Wilhelm-Erkens2000for more details of the deblending).The measured line ratios of NV1240/CIV1549and NV1240/HeII1640are compared to theoretical predictions(Fig.1).Both line ratios are in good agreement with results obtained by Hamann&Ferland(1992, 1993)for quasars at similar redshift.The measured line ratios were used to calculate an average line ratio yielding NV1240/CIV1549=0.7±0.3and NV1240 /HeII1640=5.9±3.6.The dotted lines in Fig.1indicate the line ratios expected for typical conditions of the broad emission line region(BELR)assuming solar metallicities(Hamann&Ferland1999).The observed line ratios are obviously larger than those for solar metallicities indicating super-solar abundances.Thetionsorinto numerical models of the BELR.They varied the slope of the IMF,the evo-lutionary time scale for the star formation,as well as the low mass cutoffof the IMF.They concluded that the high metallicities observed in high redshift quasars can be achieved only in models with rapid star formation(RSF)and a shallow IMF(slightly favoring massive stars compared to the solar neighbor-hood),comparable to models of giant elliptical galaxies.It is reassuring that the rapid star formation scenario indicates the same range of metallicities based on both the NV1240/CIV1549and NV1240/HeII1640line ratios.We estimated an abundance of Z≃8±4Z⊙given by our observed NV/CIV and NV/HeII within the framework of the RSF model(cf.,Dietrich&Wilhelm-Erkens2000).3.2.MgII2798vs.FeII UV Line RatioThe line ratio ofα-element vs.iron emission can be used as a cosmological clock because the time scales for the release ofα-elements and iron to the interstellar medium are significantly different.The enrichment delay is of the order of∼1Gyr(cf.,Wheeler et al.1989;Yoshii et al.1998).The best indicator ofα-High Redshift Quasars5et al.1994;Kawara et al.1996;Taniguchi et al.1997;Yoshii et al.1998;Mu-rayama et al.1998).Recently,Thompson et al.(1999)studied a few quasars at average redshifts of z=4.5,respectively.They found no significant difference in the strength of the ultraviolet FeII emission relative to MgII2798, which suggests an age of the universe of more than1Gyr at z≃4.5.In contrast to earlier studies,our data cover a much wider range of rest frame wavelengths,λλ2100−5600˚A andλλ2100−4300˚A,(Fig.2).These wide and continuous wavelength range enabled us to investigate the strong ultraviolet FeII emission based on a reliable continuumfit which was hard to achieve in earlier studies with smaller and non-continuous wavelength coverage.Due to the huge number of individual FeII emission lines(∼105)it is not practical to treat them individually.As suggested and demonstrated by Wills, Netzer,&Wills(1985),the reconstruction of a quasar spectrum by several well defined components,i.e.(i)a power law continuum,(ii)a Balmer continuum emission spectrum,(iii)a template for the FeII emission,and(iv)a template spectrum for the broad emission lines,is the best approach to measuring the strength of the FeII emission.We are presently involved in a collaboration(cf., Verner et al.1999)to use state-of-the-art computer models as well as empiricalComparisonquasars in the local universe,we compared the restframe quasar spectra in our samples(z=4.5)to a mean quasar spectrum.The mean quasar spectrum was calculated from a subset of a large quasar sample(>700quasars) which we compiled from ground-based observations and from archive spectra measured with IUE and HST(Dietrich&Hamann2001).The mean spectrum used for this comparison is based on101quasars with i)redshift z≤2,and ii) luminosities in the same range as our z=4.5quasars.The mean quasar spectra of our samples at z≃4.5are shown in Fig.2together with power law continuumfits.The continuumfits were subtracted and the pure emission lineflux was compared.For wavelengthsλ≥3200˚A much of the emission can be attributed to Balmer continuum emission, but forλ≤3200˚A most of the emission is due to broad FeII emission features (Fig.3).The relative emission strength of the FeII emission of the mean high redshift quasars are nearly identical(∼<15%)compared to the mean z≤2quasar (Fig.3).The mean quasar spectra at z≃4.5themselves differ by less than∼20%.This can be taken as an indication for no significant evolution inα-element vs.iron in quasars from the local universe to z∼4.5.High Redshift Quasars7Figure4.Estimate of z f for several combinations ofΩM andτevol(H o=65km s−1Mpc−1).The three solid lines show the age of theuniverse as a function of redshift(ΩM=0,0.3,1).The long dashedline shows the effect ofΩΛ=0.7on the age(ΩM=0.3).The lengthof the horizontal lines in the upper part of thefigure marks z f forτevol=0.5,1,2Gyrs(ΩM=0and0.3,respectively).The horizontal linesin the lower part of thefigure show the same but starting now at anaverage redshift of z=4.5.4.Summary and DiscussionThe presented study of quasars at redshifts z≃3provides evidence for higher solar abundances of the line emitting gas.This result is based on the emission line ratios of NV1240vs.CIV1549and ing assumptions on stellar evolution time scales which are necessary to produce solar or higher metallicities, the beginning of thefirst star formation epoch can be estimated.In Fig.4the age of the Universe is displayed as a function of redshift z for several settings of H o andΩM.With an evolutinary time scale ofτevol≃1Gyr(ΩM=0.3) orτevol≃2Gyrs(ΩM=0)based on normal chemical evolution models,the beginning of thefirst violent star formation episode can be dated to a redshift of z f≃6−8based on NV1240/CIV1549and NV1240/HeII1640(Fig.4).Assuming an evolutionary time scale ofτevol≃1Gyr for the progenitor stars of type SN Ia,we used the MgII2798/FeII UV emission ratio as a tracer of star formation history.The similar MgII/FeII UV emission ratios in our high redshift quasars compared to local quasars suggests an age of the universe of ∼1Gyr at z≃4.5,implying a redshift of z f≃8−15(ΩM=0−0.3)for the epoch of thefirst substantial star formation.The measured MgII/FeII UV emission ratio probably also suggests at least solar abundances.We concluded,therefore,that high redshift quasars indicate a redshift of z f≃10for thefirst major star formation epoch,corresponding to an age of the universe of∼<5·108yrs(H o=65km s−1Mpc−1,ΩM=0.3,ΩΛ=0.7).High Redshift Quasars8 ReferencesBaldwin,J.A.,Ferland,G.J.,Korista,K.T.,et 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一些关于宇宙的简单的知识英语作文英文回答：The Universe: A Vast and Mysterious Place.The universe is a vast and mysterious place, full of wonders that we are only beginning to understand. It is estimated to be around 13.8 billion years old and contains billions of galaxies, each with billions of stars. The universe is constantly expanding, and scientists believethat it will continue to do so for billions of years to come.One of the most fascinating things about the universeis its diversity. There are galaxies of all shapes and sizes, from small dwarf galaxies to massive elliptical galaxies. There are also a variety of stars, from small red dwarfs to massive blue giants. And there are planets, moons, asteroids, and comets, all orbiting around their respective stars.The universe is also home to a variety of phenomena, such as black holes, quasars, and supernovae. Black holes are regions of space with such intense gravity that nothing, not even light, can escape. Quasars are extremely bright objects that are powered by the accretion of matter onto a supermassive black hole. Supernovae are the explosions of massive stars that can release more energy in a few seconds than the sun will release in its entire lifetime.The universe is a vast and complex place, and we areonly beginning to understand its mysteries. But as we continue to explore and learn, we are gaining a greater appreciation for the beauty and wonder of our universe.中文回答：浩瀚而神秘的宇宙。

小学上册英语第2单元真题英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.My _____ (表妹) enjoys playing with her stuffed animals every day. 我表妹每天都喜欢玩她的毛绒玩具。

2. A compound is a substance formed when two or more elements are _____ chemically.3. A kitten's purring is very ______ (放松).4.He is a musician, ______ (他是一位音乐家), playing in a local band.5.What do we call the place where we watch movies?A. TheaterB. MuseumC. LibraryD. Park6.I enjoy _____ (reading/watching) movies.7. A ______ has a symbiotic relationship with flowers.8.Protecting endangered ______ (植物物种) is vital for preservation.9.The rainbow trout is a beautiful _________ (鱼).10.My sister is a _____ (演员) who loves performing.11.The ____ is a gentle giant that enjoys eating grass.12.What do we call a written record of someone's life?A. BiographyB. AutobiographyC. MemoirD. Journal13.In ancient China, the __________ Dynasty was known for its inventions. (汉朝)14.My sister has a knack for ____ (fashion).15.The ____ has a distinctive call and can be loud.16.What do you call an animal that eats both plants and meat?A. HerbivoreB. CarnivoreC. OmnivoreD. InsectivoreC17.The __________ (历史的测试) assesses understanding.18.The _____ (糖果) is very sweet.19.My brother is learning to play the ____ (accordion).20.The __________ is a region known for its festivals.21.I think learning about different cultures expands our __________.22.The __________ helps to protect the brain.23.I love to paint my toy ____ in bright colors. (玩具名称)24. A _______ can be very useful in cooking.25.I enjoy playing ________ (乒乓球) in the park. It helps me stay ________ (健康).26.My brother is a ______. He enjoys building things.27.The __________ is a major mountain range that runs through Asia. (喜马拉雅山脉)28. A _______ is a great addition to any garden.29.My brother is known for his __________ (勇气).30.Which fruit is known for having seeds on the outside?A. StrawberryB. BlueberryC. RaspberryD. BlackberryA31.The leaves change _______ in the fall, creating a beautiful view.32.Certain types of grass are perfect for ______. (某些类型的草非常适合草坪。

英译汉第三次翻译练习班级：学号：姓名：Virtually everything astronomers know about objects outside the solar system isthe universe: neutrinos. With (as its name implies) no electric charge, and negligible mass, the neutrino interacts with otherNeutrinos can thus escape from regions of space where light and other kinds of electromagnetic radiation are blocked by matter. Furthermore, neutrinos carry with them information about the site and circumstances of their production: therefore, the detection of cosmic neutrinos could provide new information about a wide variety of cosmic phenomena and about the history of the universe. (131 words)实际上天文学家对太阳系外天体的所有认知都基于对光子——一种电磁辐射量子的探测上。

不过，还有一种遍布宇宙的辐射：中微子。

正如其名，中微子不带电荷，质量可忽略不计/微乎其微。

因为几乎不和其他粒子发生反应，中微子可以穿越整个宇宙，甚至穿越物质聚合体，也不会被吸收或发生轨迹偏离。

因此，在某些空间区域,光和其他电磁辐射会被物质阻截，中微子却可以逃逸出来。

而且，中微子携带关于它诞生地点及环境的相关信息：所以，探测宇宙中的中微子可以提供关于各种宇宙现象和宇宙史的新信息。

OG11黄皮正确句子1381. Although a surge in retail sales has raised hopes that a recovery is finally underway, many economists say that without a large amount of spending the recovery might not last.2. Of all the vast tides of migration that have swept through history, perhaps none was more concentrated than the wave that brought 12 million immigrants onto American shores in little more than three decades.3. Diabetes, together with its serious complications, ranks as the nation's third leading cause of death, surpassed only by heart disease and cancer.4. A survey by the National Council of Churches showed that in 1986 there were 20,736 female ministers, almost 9 percent of the nation’s clergy, double the figure for 1977.5. As its sales of computer products have surpassed those of measuring instruments, the company has become increasingly willing to compete for the mass market sales it would in the past have conceded to rivals.6. Like the Brontes and Brawnings, James Joyce and Vrginia Woolf are often subjected to the kind of veneration that blurs the distinction between the artist a-d the human being.7. Carnivorous mammals can endure what would otherwise be lethal levels of body heat because they have a heat-exchange network that keeps the brain from getting too hot.8. Rising inventories, if not accompanied by corresponding increases in sales, can lead to production cutbacks that would hamper economic growth.9. Sunspots, vortices of gas associated with strong electromagnetic activity, are visible as dark spots on the surface of the Sun but have never been sighted on the Sun's poles or equator.10. Unlike those in the United States, Japanese unions appear reluctant to organize lower-paid workers.11. Warning that computers in the United States are not secure, the National Academy of Sciences has urged the nation to revamp computer security procedures, institute new emergency response teams, and create a special nongovernment organization to take charge of computer security planning.12. After gradually declining to about 39 hours in 1970, the workweek in the United States has steadily increased to the point that the average worker now puts in an estimated 164 extra hours of paid labor a year.13. As Hurricane Hugo approached the Atlantic coast, it increased dramatically in strength, becoming the tenth most intense hurricane to hit the United States mainland in the twentieth century and the most intense since Camille in 1969.14. The commission has directed advertisers to restrict the use of the word "natural" to foods that do not contain color or flavor additives, chemical preserva¬tives, or anything that has been synthesized.15. The Iroquois were primarily planters, although they supplemented their cultivation of maize, squash, and beans with fishing and hunting.16. Unlike the honeybee, the yellow jacket can sting repeatedly without dying and carries a potent venom that can cause intense pain.17. None of the attempts to specify the causes of crime explains why most of the people exposed to the alleged causes do not commit crimes and, conversely, why so many of those not so exposed do.18. Computers are becoming faster, more powerful, and more reliable, and so too are modems, the devices that allow two or more computers to share information over regular telephone lines.19. In virtually all types of tissue in every animal species, dioxin induces the production of enzymes that are the organism's attempt to metabolize, or render harmless, the chemical irritant.20. Using accounts of various ancient writers, scholars have painted a sketchy picture of the activities of an all-female cult that, perhaps as early as the sixth century BC, worshipped a goddess known in Latin as Bona Dea, "the good goddess."21. Paleontologists believe that fragments of a primate jawbone unearthed in Burma and estimated to be 40 to 44 million years old provide evidence of a crucial step along the evolutionary path that led to human beings.22. The end of the eighteenth century saw the emergence of prize-stock breeding, with individual bulls and cows receiving awards, fetching unprecedented prices, and exciting enormous interest whenever they were put on show.23. Of all the possible disasters that threaten American agriculture, the possibility of an adverse change in climate is probably the most difficult to analyze.24. For members of the seventeenth-century Ashanti nation in Africa, animal-hide shields with wooden frames were essential items of military equipment, protecting warriors against enemy arrows and spears.25. The golden crab of the Gulf of Mexico has not been fished commercially in great numbers, primarily because it lives at great depths-2,500 to 3,000 feet down.26. Galileo was convinced that natural phenomena, as manifestations of the laws of physics, would appear the same to someone on the deck of a ship moving smoothly and uniformly through the water as to a person standing on land.27. Health officials estimate that 35 million Africans are in danger of contracting trypanosomiasis, or "African sleeping sickness," a parasitic disease spread by the bites of tsetse flies.28. Beyond the immediate cash flow crisis that the museum faces, its survival depends on whether it can broaden its membership and leave its cramped quarters for a site where it can store and exhibit its more than 12,000 artifacts.29. Along with the drop in producer prices announced yesterday, the strong retail sales figures released today seem to indicate that the economy, although growing slowly, is not nearing a recession.30. An inventory equal to 90 days sales is as much as even the strongest businesses carry, and then only as a way to anticipate higher prices or ensure31. Egyptians are credited with having pioneered embalming methods as long ago as 2650 BC.32. The Commerce Department announced that the economy grew during the second quarter ata 7.5 percent annual rate, while inflation eased when it might have been expected to rise.33. Although schistosomiasis is not often fatal, it is so debilitating that it has become an economic drain on many developing countries.34. Efforts to equalize the funds available to school districts, a major goal of education reformers and many states in the 1970's, have not significantly reduced the gap that exists between the richest and poorest districts.35. Federal authorities involved in the investigation have found that local witnesses are difficult to locate, reticent, and suspicious of strangers.36. In 1527 King Henry VIII sought to have his marriage to Queen Catherine annulled so that he could marry Anne Boleyn.37. In one of the bloodiest battles of the Civil War, fought at Sharpsburg, Maryland, on September 17, 1862, four times as many Americans were killed as would later be killed on the beaches of Normandy during D-Day.38. Dr. Tonegawa won the Nobel Prize for discovering how the body can constantly change its genes to fashion a seemingly unlimited number of antibodies, each targeted specifically at an invading microbe or foreign substance.39. Scientists have recently discovered what could be the largest and oldest living organism on Earth, a giant fungus that is an interwoven filigree of mushrooms and rootlike tentacles spawned by a single fertilized spore some 10,000 years ago and extending for more than 30 acres in the soil of a Michigan forest.40. The plot of The Bostonians centers on the rivalry that develops between Olive Chancellor, an active feminist, and Basil Ransom, her charming and cynical cousin, when they find themselves drawn to the same radiant young woman whose talent for public speaking has won her an ardent following.41. While larger banks can afford to maintain their own data-processing operations, many smaller regional and community banks are finding that the costs associated with upgrading data-processing equipment and with the development and maintenance of new products and technical staff are prohibitive.42. Quasars, at billions of light-years from Earth the most distant observable objects in the universe, are believed to be the cores of galaxies in an early stage of development.43. Five fledgling sea eagles left their nests in western Scotland this summer, bringing to 34 the number of wild birds successfully raised since transplants from Norway began in 1975.44. The automotive conveyor-belt system, which Henry Ford modeled after an assembly-line technique introduced by Ransom Olds, reduced the time required to assemble a Model T from a day and a half to 93 minutes.45. According to some analysts, the gains in the stock market reflect growing confidence that the economy will avoid the recession that many had feared earlier in the year and instead come in fora "soft landing," followed by a gradual increase in business activity.46. Long before it was fashionable to be an expatriate, and she remained in France during the Second World War as a performer and an intelligence agent for the Resistance.47. By providing such services as mortgages, home improvement loans, automobile loans, andfinancial advice, and by staying within the metropolitan areas, Acme Bank has become one of the most profitable savings banks in the nation.48. The report recommended that the hospital eliminate unneeded beds, consolidate expensive services, and use space in other hospitals.49. Many house builders offer rent-to-buy programs that enable a family with insufficient savings for a conventional down payment to move into new housing and to apply part of the rent to a purchase later.50. It can hardly be said that educators are at fault for not anticipating the impact of microcomputer technology: Alvin Toffler, one of the most prominent students of the future, did not even mention microcomputers in Future Shock, published in 1970.51. The Olympic Games helped to keep peace among the pugnacious states of the Greek world, for a sacred truce was proclaimed during the month of the festival.52. While all states face similar industrial waste problems, the predominant industries and the regulatory environment of each state obviously determine the types and amounts of waste produced, as well as the cost of disposal.53. Section 13(d) of the Securities Exchange Act of 1934 requires anyone who buys more than 5 percent of a company's stock to make a public disclosure of the purchase.54. When Congress reconvenes, some newly elected members from rural states will try to establish tighter restrictions on the amount of grain farmers will be allowed to grow and to encourage more aggressive sales of United States farm products overseas.55. Doctors generally agree that such factors as cigarette smoking, eating rich foods high in fats, and alcohol consumption not only do damage by themselves but also aggravate genetic predispositions toward certain diseases.56. In a plan to stop the erosion of East Coast beaches, the Army Corps of Engineers proposed building parallel to shore a breakwater of rocks that would rise six feet above the waterline and act as a buffer, absorbing the energy of crashing waves and protecting the beaches.57. Affording strategic proximity to the Strait of Gibraltar, Morocco was also of interest to the French throughout the first half of the twentieth century because they assumed that without it their grip on Algeria would never be secure.58. Once they had seen the report from the medical examiner, the investigators had no doubt that the body recovered from the river was that of the man who had attempted to escape from the state prison.59. His studies of ice-polished rocks in his Alpine homeland, far outside the range of present-day glaciers, led Louis Agassiz in 1837 to propose the concept of an age in which great ice sheets existed in what are now temperate areas.60. More and more in recent years, cities are stressing the arts as a means to qreater economic development and investing millions of dollars in cultural activities, despite strained municipal budgets and fading federal support.61. Since 1986 enrollments of African Americans, American Indians, and Hispanic Americans in full-time engineering programs in the United States have steadily increased, while the number of other students entering the field has fallen.62. A 1972 agreement between Canada and the United States reduced the amount of phosphates that municipalities are allowed to dump into the Great Lakes.63. A proposal has been made to trim the horns from rhinoceroses to discourage poachers; the question is whether tourists will continue to visit game parks to see rhinoceroses once the animals' horns have been trimmed.64. The technical term "pagination" refers to a process that allows editors, rather than printers, to assemble the page images that become the metal or plastic plates used in printing.65. The only way for growers to salvage frozen citrus is to have it quickly processed into juice concentrate before warmer weather returns and rots the fruit.66. Unlike a typical automobile loan, which requires a 15 to 20 percent down payment, a lease-loan does not require the buyer to make an initial deposit on the new vehicle.67. Defense attorneys have occasionally argued that their clients' misconduct stemmed from a reaction to something ingested, but if criminal or delinquent behavior is attributed to an allergy to some food, the perpetrators are in effect told that they are not responsible for their actions. 68. Many people, willing to admit that they lack computer skills or other technical skills, are disinclined to recognize that their analytical skills are weak.69. A report by the American Academy for the Advancement of Science has concluded that many of the currently uncontrolled dioxins to which North Americans are exposed come from the incineration of wastes.70. Displays of the aurora borealis, or "northern lights," can heat the atmosphere over the Arctic enough to affect the trajectories of ballistic missiles and induce electric currents that can cause blackouts in some areas and corrosion in north-south pipelines.71. The cameras of the Voyager II spacecraft detected six small, previously unseen moons circling Uranus, doubling to 12 the number of satellites now known to orbit the distant planet.72. Architects and stonemasons, the Maya built huge palace and temple clusters without the benefit of animal transport or the wheel.73. According to a recent poll, owning and living in a freestanding house on its own land is still a goal of a majority of young adults, as it was of earlier generations.74. Often visible as smog, ozone is formed in the atmosphere when hydrocarbons and nitrogen oxides, two major pollutants emitted by automobiles, react with sunlight.75. Salt deposits and moisture threaten to destroy the Mohenjo-Daro excavation in Pakistan, the site of an ancient civilization that flourished at the same time as the civilizations in the Nile delta and the river valleys of the Tigris and Euphrates.76. Never before had taxpayers confronted as many changes at once as they confronted in the Tax Reform Act of 1986.77. Even though the direct costs of malpractice disputes amounted to less than 1 percent of the $541 billion the nation spent on health care last year, doctors say fear of lawsuits plays a major role in health-care inflation.78. Visitors to the park have often looked up into the leafy canopy and seen monkeys sleeping on the branches, with arms and legs hanging like socks on a clothesline.79. The Parthenon was a church from 1204 until 1456, when Athens was taken by General Mohammed the Conqueror, the Turkish sultan, who established a mosque in the building and used the Acropolis as a fortress.80. New hardy varieties of rice show promise of producing high yields without the costly irrigation and application of commercial fertilizer that were required by earlier high-yielding varieties.81. In an effort to reduce their inventories, Italian vintners have cut prices; their wines are priced to sell, and they do.82. Senator Lasker has proposed legislation requiring employers to retain all older workers indefinitely or show just cause for dismissal.83. Most state constitutions now mandate that the state budget be balanced each year.84. Under the Safe Drinking Water Act, the Environ¬mental Protection Agency is required either to approve individual state plans for controlling the discharge of wastes into underground water or to force its own plan for states without adequate regulations.85. Dirt roads may evoke the bucolic simplicity of another century, but financially strained townships point out that dirt roads cost twice as much to maintain as paved roads do.86. Although early soap operas were first aired on evening radio in the 1920's, they were moved to the daytime hours in the 1930's when the evening schedule became crowded with comedians and variety shows.87. The energy source on Voyager 2 is not a nuclear reactor, in which atoms are actively broken apart, but rather a kind of nuclear battery that uses natural radioactive decay to produce power.88. The recent surge in the number of airplane flights has clogged the nation's air-traffic control system, leading to a 55 percent increase in delays at airports and prompting fears among some officials that safety is being compromised.89. Presenters at the seminar, one of whom is blind, will demonstrate adaptive equipment that allows visually impaired people to use computers.90. The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over them; the resulting flow pattern, with crests and troughs that remain stationary although the air that forms them is moving rapidly, is known as "standing waves."91. The Senate approved immigration legislation that would grant permanent residency to millions of aliens currently residing here and penalize employers who hire illegal aliens.92. Despite protests from some waste-disposal companies, state health officials have ordered that the levels of bacteria in seawater at popular beaches be measured and the results published.93. By a vote of 9 to 0, the Supreme Court awarded the Central Intelligence Agency broad discretionary powers enabling it to withhold from the public the identities of its sources of intelligence information.94. The Coast Guard is conducting tests to see whether pigeons can be trained to help find survivors of wrecks at sea.95. Unlike Schoenberg, whose 12-tone system dominated the music of the postwar period, Bartok founded no school and left behind only a handful of disciples.96. Ranked as one of the most important of Europe's young playwrights, Franz Xaver Kroetz haswritten 40 plays; his works-translated into more than 30 languages-are produced more often than those of any other contemporary German dramatist.97. Like the planets, the stars are in motion, some of them at tremendous speeds, but they are so far away from Earth that their apparent positions in the sky do not change enough for their movement to be observed during a single human lifetime.98. As rainfall an to decrease in the Southwest about the middle of the twelfth century, most of the Monument Valley Anasazi abandoned their homes to join other clans whose access to water was less limited.99. Just as reading Samuel Pepys's diary gives a student a sense of the seventeenth century-of its texture and psyche-so listening to Jane Freed’s guile less child narrator takes the operagoer inside turn-of-the-¬century Vienna.100. Bihar is India's poorest state, with an annual per capita income of $111, lower than that of the most impoverished countries of the world.101. El Nino, the periodic abnormal warming of the sea surface off Peru, is a phenomenon in which changes in the ocean and atmosphere combine to allow the warm water that has accumulated in the western Pacific to flow back to the east.102. In her book illustrations, which she carefully coordinated with her narratives, Beatrix Potter capitalized on her keen observation and love of the natural world.103. A newly developed jumbo rocket, which is expected to carry the United States into its next phase of space exploration, will be able to deliver a heavier load of instruments into orbit than the space shuttle can, and at a lower cost.104. Nuclear fusion is the force that powers the Sun, the stars, and hydrogen bombs, merging the nuclei of atoms rather than splitting them apart, as nuclear reactors do.105. Originally developed for detecting air pollutants, a technique called proton-induced X-ray emission, which can quickly analyze the chemical elements in 'almost any substance without destroying it, is finding uses in medicine, archaeology, and criminology.106. Among the objects found in the excavated temple were small terra-cotta effigies left by supplicants who were either asking the goddess Bona Dea's aid in healing physical and mental ills or thanking her for such help.107. In his research paper, Dr. Frosh, medical director of the Payne Whitney Clinic, distinguishes between mood swings, which may be violent without being grounded in mental disease, and genuine manic-depressive psychosis.108. The first decision for most tenants living in a building undergoing conversion to cooperative ownership is whether to sign a no-buy pledge with the other tenants.109. Published in Harlem, the Messenger was owned and edited by two young journalists, A. Philip Randolph, who would later make his reputation as a labor leader, and Chandler Owen. 110. In June of 1987, The Bridge of Trinquetaille, Vincent van Gogh's view of an iron bridge over the Rhone, was sold for $20.2 million, the second highest price ever paid for a painting at auction.111. A baby emerges from the darkness of the womb with a rudimentary sense of vision that would be rated about 20/500; an adult with such vision would be deemed legally blind.112. The Federal Reserve Board's reduction of interest rates on loans to financial institutions is both an acknowledgment of past economic trends and an effort to influence their future direction.113. The original building and loan associations were organized as limited life funds, whose members made monthly payments on their share and then took turns drawing subscriptions on the funds for home mortgages.114. Gall's hypothesis that different mental functions are localized in different parts of the brain is widely accepted today.115. George Sand (Aurore Lucile Dupin) was one of the first European writers to consider the rural poor legitimate subjects for literature and to portray them these with sympathy and respect in her novels.116. Out of America's fascination with all things antique has grown a market for bygone styles of furniture and fixtures that is bringing back the chaise lounge, the overstuffed sofa, and the claw-footed bathtub.117. New theories propose that catastrophic impacts of asteroids and comets may have caused reversals in the Earth's magnetic field, the onset of ice ages, the splitting apart of continents 80 million years ago, and great volcanic eruptions.118. Students in the metropolitan school district are so lacking in math skills that it will be difficult to absorb them into a city economy becoming ever more dependent on information-based industries.119. The decision by one of the nation's largest banks to admit to $3 billion in potential losses on foreign loans could mean less lending by commercial banks to developing countries and increased pressure on multigovernment lenders to supply the funds.120. It has been estimated that illiteracy costs the United States at least $20 billion a year in lost industrial output and tax revenues.121. A firm that specializes in the analysis of handwriting claims to be able, from a one-page writing sample, to assess more than 300 hundred personality traits, including enthusiasm, imagination, and ambition.122. More than 30 years ago Dr. Barbara McClintock, the Nobel Prize winner, reported that genes can "jump," like pearls moving mysteriously from one necklace to another.123. Holland spends a larger percentage of its gross national product on defending its coasts from rising seas than the United States does on military defense.124. Canadian scientists have calculated that every nine years a human being will be struck by a meteorite, while each year 16 buildings can be expected to sustain damage from such objects.125. Samuel Sewall, like other seventeenth-century colonists, viewed marriage as a property arrangement rather than an emotional bond based on romantic love.126. A wildlife expert predicts that the reintroduction of the caribou into northern Minnesota will fail if the density of the timber wolf population in that region is greater than one wolf for every 39 square miles.127. Found throughout Central and South America, the sloth hangs from trees by its long rubbery limbs, sleeping 15 hours a day and moving so infrequently that two species of algae grow on its coat and between its toes.128. Today, because of improvements in agricultural technology, the same amount of acreage produces twice as many apples as it did in 1910.129. Joan of Arc, a young Frenchwoman who claimed to be divinely inspired, turned the tide of English victories in her country by liberating the city of Orleans and persuaded Charles VII of France to claim his throne.130. As a result of medical advances, many people who might once have died in childhood of such infections as diphtheria, pneumonia, or rheumatic fever now live well into old age.131. Cajuns speak a dialect brought to southern Louisiana by the 4,000 Acadians who migrated there in 1755; their language is basically seventeenth-century French to which English, Spanish, and Italian words have been added.132. One view of the economy contends that a large drop in oil prices should eventually lead to a lowering of interest rates and of fears about inflation, a rally in stocks and bonds, and a weakening of the dollar.133. Although the term "psychopath" is popularly applied to an especially brutal criminal, in psychology it refers to someone who is apparently incapable of feeling compassion or the pangs of conscience.134. Recently implemented "shift-work equations" based on studies of the human sleep cycle have reduced sickness, sleeping on the job, and fatigue among shift workers while raising production efficiency in various industries.135. Spanning more than 50 years, Friedrich Muller's career began in an unpromising apprenticeship as a Sanskrit scholar and culminated in virtually every honor that European governments and learned societies could bestow.136. Joachim Raft and Giacomo Meyerbeer are examples of the kind of composer who receives popular acclaim while living, but whose reputation declines after death and never regains its former status.137. The company announced that its profits declined much less in the second quarter than analysts had expected and that its business would improve in the second half of the year. 138. The direction in which the Earth and the other solid planets-Mercury, Venus, and Mars-spin was determined by collisions with giant celestial bodies in the early history of the solar system.。

Ladies and Gentlemen,Good morning everyone! Today, I stand before you to embark on an extraordinary journey, one that takes us far beyond the confines of our Earthly home. We are about to explore the vast and wondrous universethat surrounds us, a place filled with mysteries and wonders waiting to be discovered. So, let's put on our imaginary space suits and set off on this incredible adventure!Our story begins on our beloved planet Earth, where we all live. Earth is just one of the countless planets orbiting around our sun, the Sun. The Sun is a medium-sized star, and it is one of the billions of stars that make up our Milky Way galaxy. The Milky Way is a spiral galaxy, and it is home to our solar system and billions of other stars, planets, asteroids, and comets.Now, let's take a closer look at our solar system. It consists of eight planets, starting with Mercury, which is the closest to the Sun. As we move outward, we encounter Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Each planet has its own unique characteristics, from the red surface of Mars to the beautiful rings of Saturn.But wait, there's more! Our solar system is just a tiny part of the Milky Way galaxy, which is about 100,000 light-years across. A light-year is a measure of distance, equal to the distance light travels in one year, which is about 9.46 trillion kilometers. The Milky Way is home to around 200 to 400 billion stars, and it is just one of many galaxies in the universe.As we look beyond our galaxy, we see a universe teeming with life and wonders. There are other galaxies, each with its own unique structure and composition. Some galaxies are spiral like our Milky Way, while others are elliptical or irregular. There are even some that are shaped like rings or lenses.One of the most fascinating objects in the universe is a black hole. A black hole is a region in space where the gravitational pull is so strong that nothing, not even light, can escape. They are formed when astar collapses under its own gravity. Black holes are incredibly dense, with the mass of millions or even billions of stars packed into a tiny space.Now, let's talk about stars. Stars are the building blocks of galaxies. They come in different sizes, colors, and temperatures. Our Sun is a yellow dwarf star, but there are also red giants, blue giants, and white dwarfs. Stars are born from clouds of gas and dust called nebulae. As they form, they undergo nuclear fusion, which is the process of combining atoms to release energy.One of the most intriguing celestial bodies is the exoplanet. An exoplanet is a planet that orbits a star outside our solar system. Scientists have discovered thousands of exoplanets, and many of them are located in the habitable zone of their stars, which means they could potentially support life. Some exoplanets are even larger than Jupiter, while others are smaller than Earth.But our journey doesn't end there. There are other cosmic phenomena that we can explore, such as supernovae, quasars, and pulsars. A supernova is a powerful explosion that occurs when a massive star reaches the end of its life. Quasars are extremely bright galaxies that emit vast amounts of energy. Pulsars are highly magnetized, rotating neutron stars that emit beams of radiation.As we travel through the universe, we learn that we are not alone. There are billions of stars and planets out there, and some of them may have life forms just like us. The search for extraterrestrial life is one of the most exciting fields in astronomy. With the help of telescopes, space probes, and other advanced technology, scientists are getting closer to answering this age-old question.In conclusion, our universe is a vast and mysterious place, filled with wonders that we can only imagine. From the tiny grains of dust on Earth to the grandeur of the cosmos, there is so much to discover. As we explore the stars and planets, we gain a deeper understanding of our place in the universe and the infinite possibilities that lie ahead.Ladies and gentlemen, let us embrace our curiosity and continue to explore the universe. Who knows what we might find? Perhaps one day, we will uncover the secrets of the cosmos and learn that we are not alone in this vast, beautiful, and mysterious universe.Thank you for joining me on this journey through the stars. Let us continue to look up and dream big, for the universe is waiting for us to explore its wonders.[End of Speech]。