Supersolar metal abundances and the Broad Line Region of Narrow-line Seyfert 1 galaxies

solar energy阅读理解what is the ma阅读理解。

Solar energy (power from the sun) is of many uses. In many pa rts of the world, people are building solar houses with large numbe rs of windows to collect the heat of the sun. Solar collectors can m ake hot water from sunlight. The rays of the sun heat water in a so lar collector, and the hot water goes into a storage tank (蓄水箱). People can use the hot water for washing or for heating their houses. In the future, people may use the rays of the sun to make electricity for their homes. They will use photovoltaic cells to make electricity from sunlight.The sun is an important "new" source of energy. It is less expe nsive than oil or nuclear energy. Furthermore, it does not cause po llution, and it is not as dangerous as nuclear power. Many people t hink that solar energy will be the answer to our future energy probl ems.1. What is the ma source of solar energy?A. The earth.B. Oil.C. The sun.D. Nuclear energy.2. A solar collector can ______.A. answer our future energy problemsB. make electricity from sunlightC. use hot water for washingD. make hot water from sunlight3. Solar energy may solve ______.A. water shortagesB. storage problemsC. future energy problemsD. future water problems4. People may use the hot water from a solar collector ______.A. for nuclear powerB. for washing and heatingC. to cause pollutionD. to change sunlight into electricity。

The Potential of Solar Energy to ReplaceFossil FuelsIn the modern era, the quest for sustainable and renewable energy sources has become paramount. Fossil fuels, once considered the backbone of the global energy sector, are now being questioned due to their environmental implications and finite nature. Solar energy, on the other hand, has emerged as a promising alternative, offering a clean, renewable, and abundant source of power. This essay explores the potential of solar energy to replace fossil fuels and the associated benefits and challenges.Solar energy is derived from the sun's radiation and converted into usable electricity through photovoltaic cells. Its primary advantage lies in its limitless supply, as the sun is expected to shine for billions of years. In contrast, fossil fuels such as coal, oil, and gas are non-renewable resources and are rapidly depleting. According to the International Energy Agency, global energy demand is projected to increase by more than 30% by 2040, further stressing the need for alternative energy sources.Solar energy also boasts significant environmental benefits. The combustion of fossil fuels releases greenhouse gases such as carbon dioxide, contributing to global warming and climate change. Solar energy, on the other hand, produces no emissions, making it a clean and environmentally friendly option. Additionally, solar panels require minimal water use and land space compared to fossil fuel-based power plants.Economically, solar energy has become increasingly competitive with fossil fuels. The cost of photovoltaic technology has decreased significantly in recent years, making it more affordable for both residential and commercial use. Governments worldwide are also offering incentives such as tax credits and feed-in tariffs to encourage the adoption of solar energy.Despite these advantages, solar energy faces some challenges that need to be addressed. One of the main challenges is the intermittency of solar radiation, which can vary depending on weather conditions and地理位置. To overcome this, energy storage systems such as batteries orpumped-hydro storage can be employed to store excess energy during sunny days and release it when needed.Another challenge is the upfront cost of installing solar panels, which can be prohibitive for some. However, with the decreasing cost of photovoltaic technology and the increasing availability of financing options, solar energy is becoming more accessible to a wider range of users.In conclusion, solar energy has the potential to replace fossil fuels as the primary source of energy in the future. Its limitless supply, cleanliness, and cost-competitiveness make it an attractive alternative. However, to fully harness the potential of solar energy, it is crucial to address the associated challenges such as intermittency and upfront costs. With continued research and innovation, solar energy could play a pivotal role in ensuring a sustainable and environmentally friendly energy future.**太阳能潜力：替代化石燃料的可行选择**在现代社会中，对可持续和可再生能源的追求变得至关重要。

广州沪教牛津版(2024版新教材)七年级英语上册Unit 5 Off to space单元测试卷时间：90分钟满分：100分一、语音（共10小题；每小题1分，满分10分）A. 找出与前面音标发音相同的单词。

1．/ ɜː / A. doct or B. act or C. f ir st D. b a nana2．/ ə / A. b ir d B. h ur t C. n er vous D. pict ureB. 找出下列每组划线部分发音不同的选项。

3．A. c a mera B. rel a tive C. probl e m D. exc e llent4．A. w or k B. nev er C. G er man D. n er vous5．A. wh ole B. wh om C. wh at D. wh ose6．A. h er B. h onest C. h ear D. h orseC. 从下列各组选项中找出重读音节位置与其他不同的一项。

7．A. excited B. able C. nervous D. camera8．A. ourselves B. pollute C. without D. picnic9．A. machine B. adult C. able D. magic10．A. return B. protect C. without D. garden二、语法选择。

（共15小题；每小题1分，满分15分）阅读下面两篇短文，按照句子结构的语法性和上下文连贯的要求，从11～25各题所给的A、B、C和D项中选出最佳选项，并在答题卡上将该项涂黑。

Sam lives in a big house in Tianhe District, Guangzhou. He works 11 at a university 12 weekdays. On Saturdays and Sundays he 13 go to work.At 14 weekend, Sam often does morning exercises at 7:30 a.m. and 15 tea in one of 16 restaurants near 17 home at 8:30 a.m. Then he usually spends two hours 18 in the library. In the afternoon, he 19 plays basketball or goes running in a park. He often has a big supper with three good friends at 6:30 p.m. When they are eating, he enjoys 20 with them 21 he wants to study 22 from others.After the meal, they often go along a river and look at the stars in the sky. And Sam is keenon 23 at night. He likes reading 24 . There 25 a book show two months later. He wants to buy some.11．A. hardly B. hard C. harder D. hardest12．A. in B. at C. on D. from13．A. does B. is C. isn’t D. doesn’t14．A. a B. an C. the D. /15．A. drink B. to drink C. drinks D. drank16．A. good B. better C. best D. the best17．A. he B. him C. his D. himself18．A. to read B. reads C. on reading D. reading19．A. some time B. some times C. sometimes D. sometime20．A. talk B. to talk C. talking D. talks21．A. or B. because C. if D. but22．A. a lot of B. a lots C. a lot D. lots of23．A. write B. writes C. to write D. writing24．A. something interesting B. interesting somethingC. anything interestingD. interesting anything25．A. is going to B. will be C. is going to have D. will have三、完形填空（共10小题；每小题1分，满分10分）阅读下面短文，掌握其大意，然后从26～35各题所给的A、B、C和D项中选出最佳选项，并在答题卡上将该项涂黑。

剑桥商务英语听说星系The Milky Way GalaxyThe Milky Way is the galaxy that contains our Solar System, with the Earth and Sun. This galaxy is a vast, spinning collection of stars, planets, dust and gas, held together by gravity. It is just one of hundreds of billions of galaxies in the observable universe.The Milky Way galaxy is estimated to contain 100-400 billion stars and have a diameter between 100,000 and 180,000 light-years. It is the second-largest galaxy in the Local Group, with the Andromeda Galaxy being larger. As with other spiral galaxies, the Milky Way has a central bulge surrounded by a rotating disk of gas, dust and stars. This disk is approximately 13 billion years old and contains population I and population II stars.The solar system is located about 25,000 to 28,000 light-years from the galactic center, on the inner edge of one of the spiral-shaped concentrations of gas and dust called the Orion Arm. The stars in the Milky Way appear to form several distinct components including the bulge, the disk, and the halo. These components are made of different types of stars, and differ in their ages and their chemicalabundances.The Milky Way galaxy is part of the Local Group, a group of more than 50 galaxies, including the Andromeda Galaxy and several dwarf galaxies. The Local Group in turn is part of the Virgo Supercluster, a giant structure of thousands of galaxies. The Milky Way and Andromeda Galaxy are moving towards each other and are expected to collide in about 4.5 billion years, although the likelihood of any actual collisions between the stars themselves is negligible.The Milky Way has several major arms that spiral from the galactic bulge, as well as minor spurs. The best known are the Perseus Arm and the Sagittarius Arm. The Sun and its solar system are located between two of these spiral arms, known as the Local Bubble. There are believed to be four major spiral arms, as well as several smaller segments of spiral arms.The nature of the Milky Way's bar and spiral structure is still a matter of active research, with the latest research contradicting the previous theories. The Milky Way may have a prominent central bar structure, and its shape may be best described as a barred spiral galaxy. The disk of the Milky Way has a diameter of about 100,000 light-years. The galactic halo is a spherical component of the galaxy that extends outward from the galactic disk, as far as 200,000 light-years from the galactic center.The disk of the Milky Way Galaxy is marked by the presence of a supermassive black hole known as Sagittarius A*, which is located at the very center of the Galaxy. This black hole has a mass four million times greater than the mass of the Sun. The Milky Way's bar is thought to be about 27,000 light-years long and may be made up of older red stars.The Milky Way is moving with respect to the cosmic microwave background radiation in the direction of the constellation Hydra with a speed of 552 ± 6 km/s. The Milky Way is a spiral galaxy that has undergone major mergers with several smaller galaxies in its distant past. This is evidenced by studies of the stellar halo, which contains globular clusters and streams of stars that were torn from those smaller galaxies.The Milky Way is estimated to contain 100–400 billion stars. Most stars are within the disk and bulge, while the galactic halo is sparsely populated with stars and globular clusters. A 2016 study by the Sloan Digital Sky Survey suggested that the number is likely to be close to the lower end of that estimate, at 100–140 billion stars.The Milky Way has several components: a disk, in which the Sun and its planetary system are located; a central bulge; and a halo of stars, globular clusters, and diffuse gas. The disk is the brightest part of theMilky Way, as seen from Earth. It has a spiral structure with dusty arms. The disk is about 100,000 light-years in diameter and about 13 billion years old. It contains the young and relatively bright population I stars, as well as intermediate-age and old stars of population II.The galactic bulge is a tightly packed group of mostly old stars in the center of the Milky Way. It is estimated to contain tens of billions of stars and has a diameter of about 10,000 light-years. The Milky Way's central bulge is shaped like a box or peanut. The galactic center, which lies within this bulge, is an extremely active region, with intense radio source known as Sagittarius A*, which is likely to be a supermassive black hole.The Milky Way's halo is a spherical component of the galaxy that extends outward from the galactic disk, as far as 200,000 light-years from the galactic center. It is relatively sparse, with only about one star per cubic parsec on average. The halo contains old population II stars, as well as extremely old globular clusters.The Milky Way's spiral structure is uncertain, and there is currently no consensus on the nature of the Milky Way's spiral arms. Different studies have led to different results, and it is unclear whether the Milky Way has two, four, or more spiral arms. The Milky Way's spiral structure is thought to be a major feature of its disk, and it may berelated to the generation of interstellar matter and star formation.The Milky Way's spiral arms are regions of the disk in which the density of stars, interstellar gas, and dust is slightly higher than average. The arms are thought to be density waves that spiral around the galactic center. As material enters an arm, the increased density causes the material to accumulate, thus causing star formation. As the material leaves the arm, star formation decreases.The Milky Way's spiral arms were first identified in the 1950s, when radio astronomers mapped the distribution of gas in the Milky Way and found that it was concentrated in spiral patterns. Since then, astronomers have used a variety of techniques to study the Milky Way's spiral structure, including observations of the distribution of young stars, star-forming regions, and interstellar gas and dust.One of the key challenges in studying the Milky Way's spiral structure is that we are located within the disk of the galaxy, which makes it difficult to get a clear view of the overall structure. Astronomers have had to rely on indirect methods, such as measuring the distances and motions of stars and gas clouds, to infer the shape and structure of the galaxy.Despite these challenges, our understanding of the Milky Way's spiral structure has advanced significantly in recent years, thanks tonew observations and more sophisticated modeling techniques. Ongoing research is continuing to shed light on the nature and evolution of the Milky Way's spiral arms, and the role they play in the overall structure and dynamics of the galaxy.。

超导合金英文作文英文：Superconducting alloys are materials that exhibit zero electrical resistance and perfect diamagnetism at low temperatures. They have various applications in fields such as power transmission, magnetic levitation, and superconducting magnets. One example of a superconducting alloy is Nb3Sn, which is composed of niobium and tin. This alloy has a critical temperature of around 18 K, which means it can superconduct at temperatures below this value.Superconducting alloys have several advantages over conventional conductors. Firstly, they can carry much higher currents without any energy loss due to resistance. This means they are much more efficient and can save a lot of energy. Secondly, they can produce much stronger magnetic fields, which is useful in applications such as MRI machines and particle accelerators. Finally, they can be used to create levitation systems, which can be used totransport objects without any friction.However, superconducting alloys also have some disadvantages. Firstly, they are expensive to produce and require specialized equipment and techniques. Secondly,they are very brittle and can easily break under mechanical stress. Finally, they require very low temperatures to operate, which can be difficult to achieve and maintain.Despite these challenges, superconducting alloys have many potential applications and are an active area of research. For example, researchers are working ondeveloping superconducting wires that can be used in power transmission, which could greatly improve the efficiency of the electrical grid. They are also working on developing superconducting magnets that can be used in fusion reactors, which could provide a clean and sustainable source of energy.中文：超导合金是一种在低温下表现出零电阻和完美的抗磁性的材料。

“PEP”2024年小学3年级上册英语第5单元寒假试卷[含答案]考试时间：100分钟（总分:140）B卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、听力题：They are ___ their bikes. (riding)2、What shape has three sides?A. SquareB. TriangleC. CircleD. Rectangle答案: B3、填空题：My favorite character is __________ (超级英雄) because he is very brave.4、听力题：A physical change does not produce a new ______.5、听力题：The ______ is known for her motivational speeches.6、听力题：A saturated solution contains the maximum amount of ______.7、选择题：What is the largest planet in our solar system?A. EarthB. MarsC. JupiterD. Venus8、听力题：The ______ is the force that holds atoms together in a molecule.9、What is the name of the area around a star where conditions might be right for life?A. Goldilocks ZoneB. Habitable ZoneC. Life ZoneD. Safe Zone10、What is the main ingredient in sushi?A. NoodlesB. RiceC. BreadD. Potatoes答案:B11、听力题：The process of extracting metals from ores is called _______.12、What is the largest planet in our solar system?A. EarthB. JupiterC. SaturnD. Mars13、What is the main purpose of a compass?A. To measure distanceB. To find directionC. To show timeD. To calculate speed14、填空题：In ancient Rome, people used to watch _____ (gladiator) fights in the arena.15、填空题：I enjoy learning about different ______ (历史人物) and their contributions to society. It inspires me.16、选择题：What do we call a large body of water surrounded by land?A. LakeB. OceanC. SeaD. River17、填空题：A _____ (自然观察) can reveal many secrets of plant life.18、听力题：The __________ is a critical area for studying the impacts of climate change.19、听力题：The ______ grows in forests.20、听力题：The first space shuttle launch was in _______.21、听力题：A solar eclipse happens when the ______ passes between the Earth and the sun.22、填空题：I like to drink ______ (果汁) in the morning with my breakfast.23、Which of these is not a vegetable?A. CarrotB. TomatoC. BananaD. Spinach答案:C24、听力题：Salt is an example of a ______ formed from an acid and a base.25、填空题：I have a _____ (拼图) of a beautiful landscape that I enjoy completing.我有一个美丽风景的拼图，喜欢完成它。

地球化学资料1地球化学资料（1120101）第⼀章地球化学定义DefinitionB.И.韦尔纳茨基（1922）：地球化学科学地研究地壳中的化学元素(chemical elements)，即地壳的原⼦，在可能的范围内也研究整个地球的原⼦。

地球化学研究原⼦的历史、它们在时间和空间上的运动(movement)和分配(partitioning)，以及它们在整个地球上的成因(origin)关系。

V.M.费尔斯曼（1922）：地球化学研究地壳中化学元素---原⼦的历史及其在⾃然界各种不同的热⼒学(thermodynamical)与物理化学条件(physical-chemical conditions)下的⾏为。

V.M.哥尔德施密特（1933）：地球化学是根据原⼦和离⼦的性质，研究化学元素在矿物、矿⽯、岩⽯、⼟壤、⽔及⼤⽓圈中的分布和含量以及这些元素在⾃然界中的迁移。

地球化学的主要⽬的，⼀⽅⾯是要定量地确定地球及其各部分的成分，另⼀⽅⾯是要发现控制各种元素分配的规律(laws governing element distribution and partitioning)。

V.V.谢尔宾娜(1972):研究地球的化学作⽤的科学---化学元素的迁移、它们的集中和分散，地球及其层圈的化学成分、分布、分配和化学元素在地壳中的结合。

（地球化学基础）涂光炽（1985）：地球化学是研究地球（包括部分天体celestial bodies）的化学组成(chemical composition)、化学作⽤（chemical process）和化学演化（chemical evolution)的科学。

刘英俊等（1987）：地球化学研究地壳（尽可能整个地球）中的化学成分和化学元素及其同位素在地壳中的分布、分配、共⽣组合associations、集中分散enrichment-dispersion及迁移循徊migration cycles规律、运动形式forms of movement和全部运动历史的科学。

The Mystery and Applications of Light on MetalsLight, a fundamental aspect of our universe, interacts with matter in a multitude of fascinating ways. When light interacts with metals, the results are particularly intriguing, giving rise to a range of applications that span from everyday life to cutting-edge technologies.Metals, being made up of a dense array of atoms, exhibit a unique optical behavior known as metallic reflection. This is the reason why metals appear shiny and reflective. When light strikes a metal surface, the electrons within the metal are excited, causing them to oscillate in unison. This collective oscillation of electrons, known as a plasmon, results in the reflection of light, giving metals their characteristic光泽.Apart from their reflective properties, metals also exhibit another remarkable optical phenomenon known as absorption. Depending on the wavelength of light, certain metals can absorb specific colors, giving them a characteristic hue. For instance, gold absorbs blue light and reflects yellow-orange light, thus explaining its rich golden hue.The interaction of light with metals finds applications in various fields. One such application is in the field of optics, where metals are used to create high-quality mirrors and lenses. Metals' ability to reflect light makes them ideal for such applications, as they can produce clear and distortion-free images.Another application of light-metal interaction is in the realm of photonics, which deals with the generation, control, and detection of light. Metals are used in photonic devices such as lasers and photodiodes, where they play a crucial role in amplifying or detecting light signals.Additionally, the unique optical properties of metals are exploited in the field of plasmonics, which aims to control and manipulate light at the nanoscale. Plasmonic devices, such as plasmonic antennas and sensors, utilize the collective oscillation of electrons in metals to enhance or manipulate light-matter interactions, leading to a range of applications in areas like biosensing, imaging, and photovoltaics.In conclusion, the interaction of light with metals gives rise to a fascinating array of optical phenomena that have found applications in various fields. From creating high-quality optical devices to manipulating light at the nanoscale, the study of light-metal interaction continues to reveal new insights and potential applications that hold promise for future technological advancements.。

太阳能英语作文六级作文Title: Embracing Solar Energy for a Sustainable Future。

In recent years, the global community has increasingly recognized the importance of renewable energy sources in mitigating climate change and achieving sustainable development. Among these sources, solar energy stands outas a promising solution due to its abundance, accessibility, and environmental friendliness. In this essay, we will explore the significance of solar energy and its potentialto shape a more sustainable future.First and foremost, solar energy offers a renewable and inexhaustible source of power. Unlike fossil fuels, which are finite and contribute to greenhouse gas emissions,solar energy relies on the continuous and abundantradiation from the sun. This means that harnessing solar power does not deplete natural resources or exacerbate environmental degradation. As concerns about climate change intensify, transitioning to renewable energy sources likesolar power becomes imperative for reducing carbon emissions and curbing global warming.Furthermore, solar energy technology has experienced significant advancements in recent years, making it more efficient and affordable than ever before. Innovations in photovoltaic (PV) cells and solar panel design have dramatically increased the efficiency of convertingsunlight into electricity, while economies of scale have lowered the cost of solar installations. As a result, solar energy has become increasingly competitive with conventional energy sources, particularly in regions with ample sunlight. This trend is further reinforced by government incentives, such as subsidies and tax credits, which incentivize investment in solar infrastructure.Moreover, the decentralized nature of solar energy makes it a highly resilient and versatile solution for meeting diverse energy needs. Unlike centralized power plants that rely on extensive transmission networks, solar installations can be deployed at various scales, from individual households to large-scale solar farms. Thisdistributed generation model enhances energy security by reducing reliance on centralized infrastructure and minimizing the risk of widespread power outages. Additionally, off-grid solar systems provide a lifeline for remote communities and developing regions without access to reliable electricity, empowering them to improve their living standards and economic opportunities.In addition to its environmental and economic benefits, solar energy also offers social advantages by promoting energy equity and inclusivity. By democratizing energy production and consumption, solar power empowersindividuals and communities to take control of their energy future. Through initiatives such as community solarprojects and rooftop solar programs, households and businesses can participate in the transition to clean energy while reaping the financial rewards of reducedutility bills and energy independence. Furthermore, investing in solar infrastructure creates job opportunities across the entire value chain, from manufacturing and installation to maintenance and research, thereby stimulating economic growth and fostering a skilledworkforce.Nevertheless, realizing the full potential of solar energy requires concerted efforts from policymakers, businesses, and society as a whole. Governments play a crucial role in setting ambitious renewable energy targets, implementing supportive policies, and facilitating research and development initiatives. Similarly, businesses have a responsibility to invest in sustainable practices and technologies, including the adoption of solar energy solutions in their operations. At the same time,individuals can contribute to the transition to solar energy by making informed choices about energy consumption, advocating for renewable energy policies, and embracing energy-efficient lifestyles.In conclusion, solar energy holds immense promise as a sustainable and environmentally friendly alternative to fossil fuels. By harnessing the power of the sun, we can reduce our dependence on finite resources, mitigate climate change, and create a more equitable and resilient energy system. However, realizing this vision requires collectiveaction and commitment to accelerating the adoption of solar energy technologies. Through collaboration and innovation, we can pave the way towards a brighter and more sustainable future for generations to come.。

五年级天文知识英语阅读理解25题1<背景文章>The Sun is a very important star in our solar system. It is a huge ball of hot gas. The Sun is extremely bright and gives off a lot of heat and light. Without the Sun, life on Earth would not be possible.The Sun is made up of mostly hydrogen and helium. It is constantly undergoing nuclear reactions that release a tremendous amount of energy. This energy travels through space and reaches Earth, providing warmth and light for all living things.The Sun also has sunspots, which are areas that appear darker on the surface. Sunspots are caused by intense magnetic activity. Sometimes there are solar flares and prominences, which are powerful eruptions on the Sun.1. The Sun is mainly made up of ___.A. oxygen and nitrogenB. hydrogen and heliumC. carbon and oxygenD. nitrogen and carbon答案：B。

小学上册英语上册试卷(含答案)英语试题一、综合题(本题有50小题，每小题1分，共100分.每小题不选、错误，均不给分)1 What do you call a place where you can borrow books?A. LibraryB. BookstoreC. SchoolD. Office答案:A2 I enjoy going to the ______ (公园) to relax and unwind.3 What do we call a person who studies stars and planets?A. BiologistB. GeologistC. AstronomerD. Meteorologist答案: C4 The ________ (果实采摘) is enjoyable.5 I saw a rainbow in the ______ (天空) after the rain. It had many ______ (颜色).6 What do you call a collection of stars?A. GalaxyB. PlanetC. AsteroidD. Comet答案:A7 The _____ (袋鼠) jumps high.8 I enjoy visiting historical ______ (遗址) to learn about the past. It’s fascinating to see how people lived long ago.9 The ________ was a landmark event in the history of social justice movements.10 What is the name of the famous Italian explorer who discovered America?A. Christopher ColumbusB. Marco PoloC. Ferdinand MagellanD. Vasco da Gama答案: A11 The owl is ______ (夜间活动的) and hunts at night.12 The owl has excellent _________. (听力)13 Many plants play an important role in ______ (生态平衡).14 What is the name of the galaxy we live in?A. AndromedaB. Milky WayC. TriangulumD. Whirlpool答案：B15 What is the natural habitat of penguins?A. ForestB. DesertC. Polar RegionsD. Ocean16 I want to be a _______ (科学家) when I grow up.17 I can ___ my favorite song. (sing)18 The _______ (鸭子) quacks when it's happy.19 Which planet is known for its rings?a. Earthb. Jupiterc. Saturnd. Mars答案:c20 I want to learn how to _______ (制作) movies.21 Did you hear the _____ (小狗) yapping excitedly?22 I saw a ________ in the park.23 I enjoy ______ (学习) new things.24 My favorite dish is ______ (沙拉).25 What do you call a place where you can see many animals?A. ZooB. ParkC. GardenD. Farm答案:A26 How many days are in a leap year?A. 364B. 365D. 367答案: C27 My _____ (表哥) is coming to visit.28 She is _____ (watching) a movie.29 What do we use to write on paper?A. BrushB. PencilC. ScissorsD. Eraser30 Which fruit is yellow?A. AppleB. BananaC. CherryD. Grape31 What sound does a dog make?A. MeowB. RoarC. BarkD. Moo32 The __________ (moon) affects the tides in the ocean.33 The _____ (car/bike) is red.34 What is 7 + 3?A. 9B. 10D. 12答案:B. 1035 The teacher gives us ______ for homework. (assignments)36 The Cold War was a period of tension between _______ and the West.37 The __________ (环境保护) ensures a better future.38 What do we call the opposite of ‘happy’?A. SadB. GladC. JoyfulD. Cheerful39 The __________ was a significant time of change in Europe. (文艺复兴)40 Which animal is known for its ability to hop?A. ElephantB. FrogC. KangarooD. Cheetah答案:C41 I like to read ___ (books/magazines).42 The chemical symbol for zinc is _______.43 My sister is a great __________. (演讲者)44 The center of our solar system is the ______.45 The ______ teaches us about economics.46 A ______ (海豹) enjoys playing in the water.47 The _______ (鲸鱼) is a gentle giant.48 wildlife corridor) connects habitats for animals. The ____49 What do we call a person who designs buildings?A. ArchitectB. EngineerC. ConstructorD. Developer50 My family celebrates ______ (生日) with a big cake and lots of ______ (礼物). It's always a fun time.51 My teacher always encourages me to do my __________ (最好).52 The movie was _______ and exciting.53 The _______ (孔雀) shows its feathers.54 My favorite _____ is a soft teddy bear.55 What is the name of the famous American singer known for her hit "I Will Always Love You"?A. Mariah CareyB. Whitney HoustonC. Celine DionD. Tina Turner答案:B56 Rivers can carve canyons into the landscape through the process of ______.57 The __________ (历史的教育内容) shape future leaders.58 My dad works in an ________.59 I want to _______ my grandparents.60 My grandma loves to __________. (园艺)61 My brother loves to work on __________ (项目) with me.62 The clock shows ___ (two/three) o'clock.63 What do you call a person who cures animals?A. VeterinarianB. DoctorC. ScientistD. Farmer64 A goat can eat ______ (草) and climb steep hills.65 The __________ (历史的回想) brings clarity.66 A ________ is a large area of land that is covered in snow.67 The _______ (小鳐鱼) glides gracefully in the water.68 We measure temperature in degrees ______.69 The __________ is a famous mountain range in Asia.70 What is the name of the river that runs through Egypt?A. NileB. AmazonC. MississippiD. Yangtze答案:A71 My brother is learning to play the ____ (banjo).72 The ________ is a beautiful flower.73 The capital of the United Arab Emirates is ________ (阿布扎比).74 What is the common name for the end of a pencil?A. LeadB. TipC. EraserD. Barrel答案:A75 ________ (植物食物) supports many creatures.76 What is a synonym for "happy"?A. SadB. JoyfulC. AngryD. Tired答案: B77 What do you call a person who repairs pipes?A. ElectricianB. MechanicC. PlumberD. Carpenter答案:C78 I like to call my dog ____.79 She has ________ (short) nails.80 What is 9 4?A. 3B. 4C. 5D. 6答案:B81 My favorite game is ______ (国际象棋). I enjoy thinking carefully about my ______ (策略).82 The bear catches fish in the _________. (河流)83 Which of these is a type of cloud?A. CumulusB. MountainC. ValleyD. Desert答案:A84 A ladybug is a small _______ that brings good luck.85 The __________ (生态破坏) must be addressed.86 My dog enjoys rolling in the _______ (草).87 I have a toy _______ that can dig in the dirt.88 The _______ can help inspire creativity in children.89 What is the main source of energy for the Earth?A. WindB. SolarC. WaterD. Coal答案:B90 The __________ (历史的启示) can guide future actions.91 The process of plants making food using sunlight is called _______.92 What is the main ingredient in a salad?A. ChickenB. LettuceC. RiceD. Bread93 I enjoy reading ______ (书) before bedtime. They take me to different ______ (世界).94 The ____ is known for its ability to glide through the air.95 I enjoy ___ (photography).96 What is the term for an animal that only eats meat?A. HerbivoreB. OmnivoreC. CarnivoreD. Insectivore答案:C97 The process of a liquid becoming a gas is called ______.98 I can use my __________ (玩具名) to __________ (动词).99 I have a collection of toy _____.100 What is the name of the first artificial satellite launched into space?A. Sputnik 1B. Explorer 1C. Vanguard 1D. Luna 1。

1. Introduction An accurate and precise model of the chemical and isotopic composition of the Earth can yield much information regarding its accretion processes, and global-scale differentiation processes, including: core segregation, possible mineral fractionation in a primordial magma ocean and crust-mantle differentiation. With such a model we can also constrain compositional estimates for present-day reservoirs in the Silicate Earth and thus provide insights into their evolution. (The terms Silicate Earth and Primitive Mantle are synonymous.) There are three main approaches which have been used to model the composition of the Earth: ( 1) using the seismic profile of the core and mantle and their interpretation; (2) comparing the compositional systematics of primitive meteorites and the solar photosphere to constrain the solar nebula composition and from this estimate the composition of the inner rocky planets; and ( 3 ) using chemical and petrological models of peridotite-basalt melting relations (i.e. the pyrolite model). The seismic velocity structure of the Earth, in combination with mineral physics data for phases at the appropriate pressures and temperatures, provide important information about the average density and from this the bulk composition of the crust, mantle and core. These data yield basic insights into the gross compositional characteristics of these regions, but cannot be used to constrain the minor- and trace-element composition of the Earth. Compositional models based on primitive meteorites relates elemental abundances in the bulk Earth to those observed in chondritic meteorites in general, but particularly the CI carbonaceous chondrites, the most primitive of the chondritic meteorites. These meteorites are free of chondrules, possess the highest abundances of the moderately-volatile and volatile elements rela-

27、填空题： A ________ (园艺展览) showcases talents.
28、听力题： Electrons are found in the ________ of an atom.
29、 (46) is located at the equator. 填空题： The ____
30、填空题： The koala eats _________. (桉树叶)
5、听力题： The children are ______ in the swimming pool. (playing)
6、What do you call the first meal of the day? A. Lunch B. Breakfast C. Dinner D. Snack
7、听力题： The movie was very ___ (interesting).
包头“PEP”2024年小学英语第三单元期中试卷
考试时间：90分钟（总分:ቤተ መጻሕፍቲ ባይዱ10）A卷
考试人：_________ 题号 一 二 三 四 五 总分 得分
一、综合题(共计100题)
1、听力题： I want to ________ (meet) new friends.
2、What do you call a person who studies the environment? A. Ecologist B. Naturalist C. Biologist D. All of the above 答案: D
25、What is 12 + 8? A. 18 B. 20 C. 22 D. 24
26、What is the name of the famous American singer known as the "King of Pop"? A. Elvis Presley B. Michael Jackson C. Frank Sinatra D. Prince

高二地球科学探测单选题50题1. Scientists believe that the Earth's crust is composed mainly of ____.A. iron and nickelB. silicate rocksC. molten magmaD. heavy metals答案：B。

解析：地球的地壳主要由硅铝酸盐岩石组成。

选项A，铁和镍主要是地核的组成成分，而不是地壳，所以A错误。

选项C，熔融的岩浆存在于地幔中，并非地壳的主要组成成分，C错误。

选项D，重金属不是地壳的主要组成部分，地壳主要是较轻的硅铝酸盐岩石，D错误。

2. In the study of the Earth's interior, we know that the mantle is ____.A. the outermost layerB. made up of solid rock that can flow slowlyC. a layer full of waterD. as hard as the crust答案：B。

解析：地幔是由能够缓慢流动的固体岩石组成的。

选项A，最外层是地壳，不是地幔，A错误。

选项C，地幔中并不充满水，C错误。

选项D，地幔中的岩石与地壳的硬度不同，地幔的岩石可以缓慢流动，不像地壳那么坚硬，D错误。

3. Which of the following statements about the Earth's core is correct?A. It is the thinnest layer of the Earth.B. It is mainly composed of granite.C. It has an outer core which is liquid and an inner core which is solid.D. It has a very low temperature.答案：C。

a r X i v :a s t r o -p h /0504008v 2 2 N o v 2005Accepted for publication in the Astrophysical JournalPreprint typeset using L A T E X style emulateapj v.6/22/04A CHANDRA SURVEY OF EARLY-TYPE GALAXIES,I:METAL ENRICHMENT IN THE ISM.Philip J.Humphrey 1and David A.Buote 1Accepted for publication in the Astrophysical JournalABSTRACTWe present the first in a series of papers studying with Chandra the X-ray properties of a sam-ple of 28early-type galaxies which span ∼3orders of magnitude in X-ray luminosity (L X ).We report emission-weighted Fe abundance (Z Fe )constraints and,for many of the galaxies,abundance constraints for key elements such as O,Ne,Mg,Si,S and Ni.We find no evidence of the very sub-solar Z Fe historically reported,confirming a trend in recent X-ray observations of bright galaxies and groups,nor do we find any correlation between Z Fe and luminosity.Except in one case we do not find evidence for a multi-phase interstellar medium (ISM),indicating that multi-temperature fits required in previous ASCA analysis arose due to the strong temperature gradients which we are able to resolve with Chandra .We compare the stellar Z Fe ,estimated from simple stellar population model fits,to that of the hot gas.Excepting one possible outlier we find no evidence that the gas is substantially more metal-poor than the stars and,in a few systems,Z Fe is higher in the ISM.In general,however,the two components exhibit similar metallicities,which is inconsistent with both galactic wind models and recent hierarchical chemical enrichment simulations.Adopting standard SNIa and SNII metal yields our abundance ratio constraints imply 66±11%of the Fe within the ISM was produced in SNIa,which is remarkably similar to the Solar neighbourhood,and implies similar enrichment histories for the cold ISM in a spiral and the hot ISM in elliptical galaxies.Although these values are sensitive to the considerable systematic uncertainty in the supernova yields,they are also in very good agreement with observations of more massive systems.These results indicate a remarkable degree of homology in the enrichment process operating from cluster scales to low-to-intermediate L X galaxies.In addi-tion the data uniformly exhibit the low Z O /Z Mg abundance ratios which have been reported in the centres of clusters,groups and some galaxies.This is inconsistent with the standard calculations of metal production in SNII and may indicate an additional source of α-element enrichment,such as Population III hypernovae.Subject headings:Xrays:galaxies—galaxies:elliptical and lenticular,cD—galaxies:abundances—galaxies:halos—galaxies:ISM1.INTRODUCTIONThe entire history of star-formation and evolution leaves its chemical signature in the hot gas of early-type galaxies.X-ray observations therefore provide a natural and powerful diagnostic tool to unlock this in-formation (e.g.Loewenstein &Mathews 1991;Mathews &Brighenti 2003).However,historically X-ray mea-surements of interstellar medium (ISM)abundances have been problematical,as typified by the so-called “Fe dis-crepancy”(Arimoto et al.1997).Early Rosat and ASCA observations of these galaxies tended to imply extremely sub-solar metal abundances (generally expressed as Z Fe ,the Fe abundance with respect to the adopted solar stan-dard,since Fe has the strongest diagnostic lines in the soft X-ray band)(e.g.Loewenstein &Mushotzky 1998),in stark contrast to ∼solar abundances in the stellar pop-ulation.Since individual galaxies are not “closed boxes”,the ISM is believed to be built up primarily through stellar mass-loss and Type Ia supernovae (SNe)ejecta.These two crucial ingredients lead classical “wind mod-els”of gas enrichment to predict highly super-solar Z Fe in these galaxies (e.g.Ciotti et al.1991;Loewenstein &Mathews 1991).The problems caused by this discrep-ancy are exacerbated further when attempting to under-stand gas enrichment in clusters of galaxies,for which X-1Department of Physics and Astronomy,University of California at Irvine,4129Frederick Reines Hall,Irvine,CA 92697-4575ray observations typically find Z Fe ∼0.3–0.5.The metal content of the intra-cluster medium (ICM)is primarily attributed to the stellar ejecta from giant elliptical galax-ies,and so it is difficult to envisage there being lower metal abundances in individual galaxies than in the ICM (Renzini 1997).Attempts to reproduce the low Z Fe in early-type galax-ies from a modelling standpoint by,for example,incorpo-rating ongoing accretion of unenriched gas (e.g.Brighenti &Mathews 1999)or allowing complex star-formation his-tories (e.g.Kawata &Gibson 2003)have not been en-tirely successful,leading some to point a finger at the spectral-modelling.Arimoto et al.(1997),for instance,called into question the plasma codes being fitted to the data,particularly in light of uncertainties associated with the Fe L-shell transitions in X-ray emission plasma codes.This point was investigated further by Matsushita et al.(2000),who argued that,having degraded the data qual-ity in the vicinity of the Fe L-shell,Z Fe ∼>0.5can be found in the highest X-ray luminosity (L X )galaxies.Consistent results from spectral-fitting with plasma codes that treat the Fe L-shell transitions differently would seem,how-ever,to conflict with this explanation (e.g.Buote et al.2003b).Although remaining errors in the treatment of the Fe L-shell in the plasma codes can be important for high-resolution spectroscopy (e.g.Behar et al.2001),at CCD resolution the effects are substantially washed out2Humphrey&Buote.so that they contribute only a∼10–20%systematic un-certainty to the abundance measurement(Buote et al. 2003b).Perhaps a more natural alternative was suggested by Buote&Fabian(1998),who demonstrated thatfitting a single temperature model to the emission spectrum of intrinsically non-isothermal hot gas gives rise to a sub-stantially under-estimated abundance(not to mention a significantly poorerfit),an effect dubbed the“Fe bias”(see also Buote2000b).This effect had previously been recognized by Buote&Canizares(1994),and Trinchieri et al.(1994)found thatfitting a two-temperature model to the Rosat spectrum of the bright elliptical NGC4636 resulted in poorly-constrained abundances which could be consistent with solar values,in contrast to low Z Fe required for single-temperaturefits.A spectrally hard (kT∼>5keV)component had long been recognized in the ASCA spectra of the many early-type galaxies,which was attributed to emission from undetected X-ray bina-ries(Matsushita et al.1994).The composite spectrum from these sources,which dominate the emission of low-L X galaxies,can typically be approximated as a pure bremsstrahlung model.Therefore,fitting only a single-temperature hot gas model to the spectra of such galax-ies also tends to give rise to unphysically low abundances (e.g.Fabbiano et al.1994;Kim et al.1996,who found es-sentially unconstrained abundances when incorporating a term to account for this effect in their Rosat analy-sis).This effect is clearly distinct from,albeit related to, the Fe bias(see discussion in Buote2000b).Although the spectral-shape of the unresolved source component is sufficiently hard that it cannot move to mitigate,even in part,the Fe bias arising from multi-temperature hot gas components,Buote&Fabian(1998)still found Z Fe consistent with solar in the lower-L X systems,in which thefit implied only a single hot gas component,plus un-detected sources.However,the poor signal-to-noise ra-tio(S/N)characteristic of the lower-L X galaxies tended to produce poorly-constrained abundances,so that very sub-solar abundances could not be ruled out.Recent Chandra and XMM measurements of abun-dances in X-ray bright galaxies and the centres of groups have tended to support∼solar or even slightly super-solar abundances for the ISM(e.g.Buote et al.2003b; Tamura et al.2003;Gastaldello&Molendi2002;Buote 2002;Xu et al.2002;O’Sullivan et al.2003;Kim&Fab-biano2004b).In contrast,very sub-solar Z Fe are still being reported in the lowest L X/L B systems(e.g.Irwin et al.2002;Sarazin et al.2001).Perhaps the most dra-matic examples of this latter effect are the three very low-L X galaxies for which O’Sullivan&Ponman(2004) reported Z Fe∼<0.1.This apparent lack of consistency in the enrichment processes operating on different scales is intriguing,and it remains to be assessed whether it is an artefact of the poorer S/N or a real effect in low-L X sys-tems.Although a major problem for our understanding of galaxy evolution,a full understanding of this effect is inhibited by the lack of interesting abundance con-straints in galaxies with L X intermediate between these two extremes.In a recent paper,Humphrey et al.(2004), we made some initial progress in this area by report-ing constraints for the normal,moderate-L X S0galaxy NGC1332and the elliptical NGC720,in both cases strongly excluding the extremely sub-solar(Z Fe∼<0.4)abundances historically reported for these systems.Cou-pled with similar constraints on the abundances in the moderate L X/L B radio galaxy NGC1316(Kim&Fab-biano2003),this would hint at a consistent picture of enrichment from cluster to moderate-L X galaxy scales. In addition to the insight into enrichment afforded from global Z Fe measurements,theα-element abundance ra-tios,with respect to Fe,provide an additional power-ful diagnostic.Different types of SNe inject material imprinted with characteristic chemical“fingerprints”,so that the measured abundance pattern can be used to as-sess the relative contribution of SNIa and SNII to ISM enrichment.Early attempts to extract this information (e.g.Matsushita et al.2000;Finoguenov&Jones2000) were largely affected by a failure to treat the Fe bias, although a significant contribution of SNIa to the en-richment process was indicated.More recently,studies with high-quality XMM and Chandra data have revealed typically∼70–90%of the ISM enrichment in the cen-tres of groups and clusters seems to have its origin in SNIa,which is close to the∼75%value in the Solar neigh-bourhood(e.g.Gastaldello&Molendi2002;Buote et al. 2003b).For NGC1332and NGC720,we were able to obtain interesting constraints on theα-to-Fe ratios in some of the lowest-L X systems to date,again inferring ∼70–80%of the Fe to have been produced in SNIa.This also supports the suggestion of homology in the enrich-ment process over different mass-scales,at least down to moderate-L X galaxies.Although these results are intriguing,it is by no means clear that the two galaxies we considered are representa-tive,nor is it clear that all X-ray bright galaxies follow the trend of∼solar abundances(e.g.Sambruna et al. 2004).Furthermore,these studies have not elucidated the processes which may be giving rise to very low-Z Fe measurements in the faintest systems.In light of these results,therefore,the next logical step is to consider a uniformly-analyzed sample of galaxies spanning a large range of L X,and particularly expanding the number of moderate-L X galaxies studied.In this paper,we present the results of a study of metal enrichment in a sample of 28early-type galaxies drawn from the Chandra archive. In subsequent papers we will discuss the gravitating mass and point-source populations of these objects as a whole. The galaxies have been carefully selected to span the available X-ray luminosity range,from group-dominant to low-L X galaxies.In many respects,Chandra ACIS is the natural instru-ment with which to undertake such a study.Although XMM has a significantly higher collecting area,the anal-ysis of faint,diffuse sources is complicated by difficulties in treating the background.Chandra also has an intrin-sic advantage in being able to resolve out a substantial fraction of the X-ray binary contribution into individual sources,which must otherwise be disentangled spectrally. The excellent spatial resolution of Chandra also provides an unprecedented opportunity to investigate any spatial temperature variation,which would provide the natural source of the Fe bias.Imaging spectroscopy at CCD reso-lution is well-suited to determine reliable abundances in a galaxy.In fact there are a number of drawbacks to using the Chandra and XMM gratings instead for such a study. The extended nature of the sources makes grating spec-troscopy extremely challenging.The significantly lowerISM abundances in early-type galaxies.3effective area of the grating spectrographs in comparison to the ACIS CCDs and,especially for the XMM RGS in-strument,the more limited bandwidth both exacerbate this problem.Although one of the key issues of inter-est is the determination of multiple temperature compo-nents in the extraction aperture,this tends to produce features broad enough to be evident in CCD spectra.In fact,based on high S/N data of the group NGC5044 there was excellent agreement in the abundances deter-mined with the XMM gratings and the XMM and Chan-dra CCDS(Buote et al.2003b;Tamura et al.2003),con-firming that CCD resolution is sufficient to obtain reli-able abundances.Throughout this paper we adopt the latest solar abun-dances standard of Asplund et al.(2004,see§4.1),which resolve several previously-noted discrepancies between “photospheric”and“meteoritic”values.All error-bars quoted refer to the90%confidence region,unless other-wise stated.2.TARGET SELECTIONBy its nature,the Chandra archive contains a nonuni-form sample of galaxies.Although this prevents our choosing a statistically complete sample,we selected28 galaxies approximately spanning the range of measured L X,from∼8×1039–1043erg s−1.We only considered relatively nearby galaxies which had been observed for a total of at least10ks with the ACIS-S or ACIS-I, and without any grating employed.For selection pur-poses X-ray luminosities were taken from the catalogue of O’Sullivan et al.(2001),although all luminosities have subsequently been recomputed in the present work (§3.2).To an initial sample of26galaxies chosen in this way,we also added two further interesting objects not in the O’Sullivan catalogue—NGC1132,one of the clos-est examples of a“fossil group”(Mulchaey&Zabludoff1999,F.Gastaldello et al,2005,in prep.)and the rela-tively isolated,moderate-L X galaxy NGC1700which has an unusually high X-ray ellipticity,which Statler&Mc-Namara(2002)argued may indicate rotational support. Two of our sample,NGC1332and NGC720,have al-ready been discussed in Humphrey et al.(2004),and we adopt the results from that work here.The sample con-tains10high-L X(log10L X∼>41.5)galaxies,12moderate-L X(log10L X≃40.5–41.5)and6low-L X(log10L X∼<40.5) galaxies.Most of the sample was observed with ACIS-S, although in a few cases ACIS-I was employed.To give ex-tra coverage at large radii both ACIS-S and ACIS-I data for the two bright galaxies NGC1399and NGC4472, were analysed together.A summary of the properties of the galaxies and details of the Chandra exposures are given in Table1.In order to provide accurate luminosity estimates,we searched the literature for reliable distance estimates.Where pos-sible,we adopted those determined from surface bright-nessfluctuations(SBF)by Tonry et al.(2001,correcting for an improved Cepheid zero-point:Jensen et al.2003) or Jensen et al.(2003).Alternatively,we used distances determined from the D n−σrelation(Faber et al.1989), or the redshift,corrected for Virgo-centricflow,as given in LEDA.We assumed H0=70km s−1Mpc−1.Of this sample,6systems(IC4296,NGC507, NGC741,NGC1399,NGC4472,NGC7619)appear to be the central galaxies in substantial,optically-identified groups so their X-ray emission may be to some extent in-tertwined with that of a surrounding intra-group medium (IGM).In the present context,it suffices to consider that all the systems comprise a continuum over a range of mass-scales.In a subsequent paper,we will discuss the is-sue of group membership,and the total gravitating mass, in detail.3.DATA REDUCTIONFor data reduction we used the CIAO3.1and Hea-soft5.3software suites,in conjunction with Chandra Caldb calibration database2.28.For spectral-fitting we used Xspec11.3.1.In order to ensure the most up-to-date calibration,all data were reprocessed from the“level 1”eventsfiles,following the standard Chandra data-reduction threads2.We applied corrections to take ac-count of a time-dependent drift in the satellite gain and, for ACIS-I observations,the effects of“charge transfer in-efficiency”,as implemented in the standard CIAO tools. To identify periods of enhanced background(“flar-ing”),which seriously degrades the signal-to-noise(S/N) and complicates background subtraction(e.g.Marke-vitch2002),we accumulated background lightcurves for each exposure from low surface-brightness regions of the active chips.We excluded obvious diffuse emission and data in the vicinity of any detected point-sources(see below).Periods offlaring were identified by eye and ex-cised.Any residualflaring which is not removed by this procedure will be sufficiently mild to have negligible im-pact in the centres of bright galaxies.However,in the fainter systems even very mild background variation can have a significant impact on our results,and so we treat these systems with extra care(§5.2).Thefinal exposure times are listed in Table1.Point source detection was performed using the CIAO tool wavdetect(Freeman et al.2002).In order to im-prove the likelihood of identifying sources with peculiarly hard or soft spectra,full-resolution images were created of the region of the ACIS focal-plane containing the S3 chip in the energy-band0.1–10.0keV and,so as to iden-tify any unusually soft or hard sources,also in the bands 0.1–3.0keV and3.0–10.0keV.Sources were detected sep-arately in each image.In order to minimize spurious detections at node or chip boundaries we supplied the detection algorithm with exposure-maps generated at en-ergies1.7keV,1.0keV and7keV respectively(although the precise energies chosen made little difference to the results).The detection algorithm searched for structure over pixel-scales of1,2,4,8and16pixels,and the de-tection threshold was set to∼10−7spurious sources per pixel(corresponding to∼0.1spurious detections per im-age).The source-lists obtained within each energy-band were combined and duplicated sources removed,and the final list was checked by visual inspection of the images.A full discussion of the point source populations will be given in a subsequent paper.In the present work,the data in the vicinity of any detected point source were removed so as not to contaminate the diffuse emission. As discussed in Humphrey&Buote(2004,see also Kim &Fabbiano2004a)a significant fraction of faint X-ray binary sources will not have been detected by this pro-cedure,and so we include an additional component to 2/ciao/threads/index.html4Humphrey&Buote.TABLE1The sampleGalaxy Type Dist D25L B log10L X N H ObsID Instr.Date Exposure (Mpc)(′)(1010L⊙)(log10(erg s−1))(1020cm−2)(dd/mm/yy)(ks) High-L X galaxiesIC4296E Radio gal50.82 3.812.141.54 4.13394S10/09/0125 NGC507SA(r)082.63 3.214.943.03 5.42882I08/01/0243 NGC741E075.83 2.914.242.32 4.42223S28/01/0130 NGC1132E98.24 2.18.342.76 5.2801S10/12/9913 NGC1399cD;E1pec18.51 6.9 4.242.09 1.3319S18/01/00564174I28/05/0345 NGC1600E357.43 3.29.842.19 4.84283S18/09/0222 NGC4472E2/S0(2)Sy215.119.77.541.52 1.7321S12/06/0032322I19/03/0010 NGC5846E0-1;LINER HII21.11 3.8 3.141.57 4.3788S24/05/0023 NGC7619E49.21 2.6 6.942.06 5.03955S24/09/0331 NGC7626E pec51.23 2.7 6.941.51 5.02074I20/08/0126 Moderate-L X galaxiesNGC720E525.71 4.6 3.141.33 1.5492S12/10/0029 NGC1332S(s)021.31 4.1 2.340.95 2.24372S19/09/0245 NGC1387SAB(s)018.91 3.3 1.240.78 1.34168I20/05/0345 NGC1407E026.81 5.3 6.541.32 5.4791S16/08/0040 NGC1549E0-118.31 4.7 2.940.66 1.52077S08/11/0022 NGC1553SA(rl)0LINER17.21 5.3 3.740.64 1.5783S02/01/0014 NGC1700E441.11† 3.0 4.641.20 4.82069S03/11/0027 NGC3607SA(s)021.21 4.5 3.440.94 1.52073I12/06/0138 NGC3923E4-521.31 6.4 4.941.03 1.51563S14/06/018.8 NGC4365E319.01 5.8 3.740.83 6.22015S02/06/0140 NGC4552E;LINER HII14.31 5.0 2.040.65 2.62072S22/04/0154 NGC5018E342.63 3.67.140.967.02070S14/04/0128 Low-L X galaxiesNGC3115S09.017.3 1.439.86 4.32040S14/06/0136 NGC3585E7/S018.61 6.1 3.340.35 5.62078S03/06/0135 NGC3608E2LINER21.31 3.2 1.740.39 1.52073I12/06/0138 NGC4494E1-2LINER15.81 4.5 2.340.36 1.52079S05/08/0115 NGC4621E517.01 5.0 2.540.14 2.22068S01/08/0125 NGC5845E24.010.90.4540.17 4.34009S03/01/0330Note.—Listed above are all of the galaxies in our sample.Distances were obtained from1—SBF:Tonry et al.(2001),corrected for the the new Cepheid zero-point(see text),2—SBF:Jensen et al.(2003),3—D n-σ:Faber et al.(1989),4—redshift distance(LEDA);†—uncertain. L B was determined from the face-on,reddening-corrected B-band magnitude given by LEDA.L X was computed in the0.1–10.0keV band self-consistently in the present work(§3.2),excluding obvious emission from any low-luminosity AGN,and extrapolating the surface brightness to a fiducial300kpc radius.The galaxy type was taken from NED.N H is the nominal Galactic column-density along the line-of-sight.We show the Chandra observation identifier(ObsID),the ACIS instrument(I or S)and the net exposure-time,having excluded periods offlaring.account for it in our spectralfitting.3.1.Background estimationOne of the key challenges in spectral-fitting diffuse X-ray emission is ensuring proper background subtraction. For Chandra a set of blank-field eventfiles have been made available as part of the standard Caldb distribu-tion,from which background spectra can be accumulated corresponding to similar regions of the detector.For each observation,we prepared from these a suitably projected background eventsfile.We were able to extract from this file“template”background spectra for each region of the detector in which our“source”spectra were obtained. However,these background spectra are unlikely to rep-resent perfectly the background in any one observation. There are known to be significant long-term secular vari-ations in the non X-ray components of the background, substantialfield-to-field variation in the cosmic compo-nent,and there may be some residual mildflaring.It is also worth noting that the hard(power law)component of the cosmic X-ray background arises from undetected background AGN,so its absolute normalization is also a strong function of the point source detection complete-ness;in turn this is a function of the surface brightness of the galaxy and the total exposure time(Kim&Fabbiano 2004a).Several authors have adopted the practice of renor-malizing the background template to ensure good agree-ment with the instrumental background at high energies (∼>10keV).Such a procedure,however,also renormal-izes the(uncorrelated)cosmic X-ray background and in-strumental line features,which can lead to serious over or under-subtraction.Given these reservations we chose to use an alternative background estimation procedure. Our method involved modelling the background,some-what akin to the approach of Buote et al.(2004).For each observation,we extracted a spectrum from a“source free”region of the ACISfield of view.We chose a∼2′region centred on the S1chip if the galaxy was cen-tred on S3,or on the S2chip where the galaxy was centred on ACIS-I.If the S1or S2chips were turned off,we chose a small,∼<1′region on the S3or ACIS-I chips,as appropriate,positioned to be in a regionISM abundances in early-type galaxies.5of as low surface-brightness as possible.We excluded data from the vicinity of any point-sources found by the source detection algorithm.Additionally,we extracted a “source+background”spectrum from the CCD on which the source was centred,in an annulus centred at the galaxy centroid and with an inner and outer radii typi-cally∼2.5′and3.3′.We adopted two spectra since we found that this procedure enabled us most cleanly to constrain the background.Some of the brightest galax-ies are so extended in the X-ray that even in our“source free”region there is a small contribution from hot gas at large radii.We found that using two spectra with different hot gas contributions allowed this to be read-ily disentangled from the actual background components. In order to constrain the model,wefitted both spectra simultaneously,without background subtraction,using Xspec.Our model consisted of a single APEC plasma (to take account of the diffuse emission from the galaxy; the“source”),plus background components.These com-prised a power law withΓ=1.41(to account for the hard X-ray background),two APEC models with solar abun-dances and kT=0.2and0.07keV(to account for the soft X-ray background)and,to model the instrumental con-tribution,a broken power law model and two Gaussian lines with energies1.7and2.1keV and negligible intrin-sic widths.We have found that this model can be used to parameterize adequately the template background spec-tra.In order to disentangle the source and background components,given the general lack of photons in these spectra,we tied the abundances and temperatures of the “source”APEC components between both extraction re-gions,but allowed the normalizations to be free.In the fainter galaxies the normalization of the source compo-nent in the“source free”region tended,as expected,to zero.We also assumed that the background model nor-malization scales exactly with the extraction area.In general,we found that this was able tofit both spectra very well.In our subsequent spectral analysis,we did not background-subtract the data using the standard tem-plates,but took into account the background by using an appropriately scaled version of this model.Even if the background spectrum varies substantially over thefield-of-view,our background modelling is most correct at largest distances from the source centroid, where the results are most sensitive to the background. In fact,we found that the standard background tem-plates fared much worse than these modelled background estimates when the data were from regions of low surface brightness.We discuss this issue further,and how the choice of background can affect our results in§5.2.3.2.L X estimationIn order to provide a self-consistent analysis of the galaxies in this sample,we obtained estimates of L X based on the Chandra data.First,we estimated the flux within our chosen spectral extraction regions from our the best-fitting spectral models(§4.3–4.4).Fluxes were computed separately for the gas and undetected point-sources in the energy-band0.1–10.0keV.Since the adopted aperture will not contain all of the diffuseflux from the galaxy,we extrapolated the emission out to a projected radius of300kpc,i.e.the Virial radius for a 1.6×1012M⊙galaxy.We assumed spherical symmetry and parameterized the surface brightness with a single or doubleβ-model.Theβ-model parameters were de-termined fromfits to the radial surface brightness in the 0.3–2.0keV band,using dedicated software which can fold in the instrumental point-spread function,which we computed at1keV.Data from the vicinity of any de-tected point-sources were excluded from thefit,and we assumed that the hot gas and undetected sources had the same radial brightness distribution.The results of the surface brightnessfits to each galaxy will be discussed in detail in a subsequent paper.This procedure typically corrects theflux upwards by a factor∼1.1–4,depending on the shape of the surface brightness profile.Since it is by no means certain that this extrapolation is valid out to∼300kpc,we expect this to introduce some uncer-tainty into the estimated L X.However,for our present purposes we believe this approach is sufficiently accurate. To compute the total L X of the galaxy,we also included theflux of all detected point-sources within the B-band twenty-fifth magnitude(D25)isophote,all of which were assumed to be associated with the galaxy for these pur-poses.Wefitted the composite spectrum of all these sources with our canonical(kT=7.3keV bremsstrahlung) model.In most cases this gave a goodfit to the data, although in a few instances a single power law or power law plus disk blackbody components were used instead to obtain a goodfit.In the event a significant low-luminosity AGN appears to be present in the galaxy(i.e. NGC1553,IC4296),we omitted theflux from the AGN. The total luminosity of the(detected,plus undetected) point-sources within D25was typically in agreement with the estimate of Kim&Fabbiano(2004a),based on ex-trapolating the resolved X-ray luminosity functions in nearby early-type galaxies.We found a mean L X(point sources)/L B∼0.9×1030erg s−1L⊙−1,in excellent agree-ment with these authors.The point-source populations will be discussed in detail in a subsequent paper. Comparing with thefluxes given in O’Sullivan et al. (2001)wefind broad agreement,although our estimates tend to be∼0.25dex higher.We attribute this discrep-ancy to differences in spectral modelling and our extrap-olation procedure.4.SPECTRAL ANALYSIS4.1.Solar abundances standard Throughout this paper,we adopt the solar photo-spheric abundances of Asplund et al.(2004),which de-viate significantly for many of the key species from the previous standard of Grevesse&Sauval(1998).The in-corporation of detailed3D line transfer modelling(and, in some cases,treatment of non-LTE conditions)has tended to reconcile so-called“meteoritic”and photo-spheric abundances(for non-volatile species),so that dis-crepancies remaining are typically at∼<0.1dex,i.e.ap-proximately the same level as the statistical uncertain-ties.We therefore adopt these abundances as our stan-dard.This does,however,introduce some complications when comparing with results reported in the literature since most authors adopt either the older abundances standard of Grevesse&Sauval(1998)or the outdated abundances of Anders&Grevesse(1989).For comparison with our work,Z Fe,Z O/Z Fe,Z Ne/Z Fe, Z Mg/Z Fe,Z Si/Z Fe,Z S/Z Fe and Z Ni/Z Fe referenced to the standard of Grevesse&Sauval(1998)should be scaled。

Eλ
=
hc λ
(3.1)
where h¯ is Plank’s constant and c is the speed of light. Only photons with sufficient energy to create an electron–hole pair, that is, those with energy greater than the semiconductor
band gap (EG), will contribute to the energy conversion process. Thus, the spectral nature of sunlight is an important consideration in the design of efficient solar cells.
The physical principles underlying the operation of solar cells are the subject of this chapter. First, a brief review of the fundamental properties of semiconductors is given that includes an overview of semiconductor band structure and carrier generation, recombination, and transport. Next, the electrostatic properties of the pn-junction diode are reviewed, followed by a description of the basic operating characteristics of the solar cell, including the derivation (based on the solution of the minority-carrier diffusion equation) of an expression for the current–voltage characteristic of an idealized solar cell. This is used to define the basic solar cell figures of merit, namely, the open-circuit voltage, VOC; the short-circuit current, ISC; the fill factor, FF; the conversion efficiency, η; and the collection efficiency, ηC. Much of the discussion here centers on how carrier recombination is the primary factor controlling solar cell performance. Finally, some additional topics relevant to solar cell operation, design, and analysis are presented. These include the relationship between band gap and efficiency, the solar cell spectral response, parasitic resistive effects, temperature effects, a brief introduction to some modern cell design concepts, and a short overview of detailed numerical modeling of solar cells.

小学上册英语第四单元期中试卷英语试题一、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.An ecosystem is a community of living organisms interacting with their ______ environment.2.I want to _____ (go/stay) home.3.My dog barks when it sees a ______ (陌生人).4.The jellybeans are ______ (colorful) and sweet.5.How many days are there in a week?A. 5B. 6C. 7D. 86.The ________ was a prominent advocate for social change.7.The chemical symbol for phosphorus is _____.8.What is the name of the famous painting by Vincent van Gogh?A. The Starry NightB. The ScreamC. Girl with a Pearl EarringD. The Last SupperA9.In science class, we learned about ________ (机器人). They can help with many________ (任务).10.The study of ancient climates is called ______.11.My brother, ______ (我哥哥), enjoys playing soccer.12.What do we call the area of land that is home to many different species?A. EcosystemB. HabitatC. BiomeD. CommunityA Ecosystem13. A _____ (园林) can be designed for relaxation.14.The ______ thrives in tropical climates.15.The __________ (历史的交汇) creates opportunities for dialogue.16.The garden is full of colorful _______ that bloom.17.Carbon is unique because it can form _____ (bonds) with many other elements.18.What is the capital of France?A. BerlinB. MadridC. ParisD. Rome19.She has a ________ (goal) to achieve.20.The ancient Greeks made significant contributions to ________.21.The __________ were a group of explorers who circumnavigated the globe. (麦哲伦的探险队)22.Plate tectonics can create mountains through a process known as ______.23.What is the main ingredient in soup?A. WaterB. VegetablesC. MeatD. All of the above24.The chemical symbol for iridium is ______.25.The ________ (植物适应性能力) is remarkable.26.The frog jumps into the ______ (pond).27.The ancient Egyptians built their pyramids as _____.28.My cousin has a __________ dog. (可爱的)29.What is 3 + 5?A. 7B. 8C. 9D. 10B30.Today is ________ (Monday).31.I like to listen to ___ (music/news).32.What is the name of the ocean that is the largest in the world?A. AtlanticB. IndianC. ArcticD. PacificD33.What is the largest organ in the human body?A. HeartB. BrainC. SkinD. LiverC34.What do you call the study of living organisms?A. PhysicsB. ChemistryC. BiologyD. AstronomyC35.Which animal is known for its stripes?A. LionB. ElephantC. ZebraD. Giraffe36.The ________ (城市建设) shapes our environment.37.The ancient Egyptians used ________ for their architectural designs.38.我的朋友喜欢 _______ (活动). 她觉得这很 _______ (形容词)39.I met my _____ (新邻居) yesterday.40.I like to ______ (关注) environmental issues.41. A base is a substance that can accept _______ ions.42.We should _______ (保持) our environment safe.43.The first Olympic Games were held in ________.44.What is the capital of Malta?A. VallettaB. MdinaC. SliemaD. BirkirkaraA Valletta45.I have a special ______ (笔) that changes color when I write.46.The chemical formula for potassium permanganate is _______.47. A _______ describes how easily an element can lose electrons.48.What is the capital of Zambia?A. LusakaB. NdolaC. KitweD. LivingstoneA49.The dog is ________ outside.50.What is the largest planet in our solar system?A. EarthB. MarsC. SaturnD. JupiterD51.The library has many ________.52.What is the name of the famous American poet known for his work "Leaves of Grass"?A. Robert FrostB. Walt WhitmanC. Emily DickinsonD. Langston HughesB53.I want to ________ (mentor) someone.54.ic sank on its maiden voyage in ________ (1912). The Tita55.The unit for measuring temperature in science is ______.56.The flower needs water and _______ (花需要水和_______).57.What do you call a group of dolphins?A. PodB. SchoolC. FlockD. Pack58.The puppy is very ______.59.I saw a _______ (小皮卡丘) in the park.60.Rockets are used to launch spacecraft into ______.61. A beam of light can be ______ by a mirror.62.My mom sings me a ____.63.I think that storytelling is a powerful way to share __________.64. A physical change does not alter the ________ of a substance.65.The train is _______ and fast.66.The ancient city of Carthage was located in present-day ______ (突尼斯).67.The Earth’s rotation takes ______ hours.68.I have a wonderful . (我有一个美好的。