from an explosion of huge stars. Stars that are near death can no longer burn due to loss of fuel，and because its temperature can no longer control the gravitational(重力的)force，hydrogen ends up putting pressure onto the star’s surface until it suddenly explodes then collapses.
2 Black holes come from stars that are made of hydrogen，other gases and a few metals. When these explode it can turn into a
stellar-mass(恒星质量)black hole，which can only occur if the star is large enough(should be bigger than the sun)for the explosion to break it into pieces，and the gravity starts to compact every piece into the tiniest particle. Try to see and compare：if a star that’s ten times the size of the sun ends up being a black hole that’s no longer than 70 kilometers，then the Earth would become black hole that’s only a fraction of an inch!
3 Objects that get sucked in a black hole will always remain there，never to break free. But remember that black holes can only gobble up(吞噬)objects within a specific distance to it. It’s possible for a large star near the sun to become a black hole，but the sun will continue to stay in place. Orbits(轨道)do not change because the newly formed black hole contains exactly the same amount of mass as when it was a star，only this its mass is totally contracted that it can end up as no bigger than a state.
4 So far，astronomers have figured out that black holes exist because of Albert Einstein’s theory of relativity. In the end，through numerous studies，they have discovered that black holes truly exist. Since black holes trap light and do not give off light，it is not possible to detect black holes via a telescope. But astronomers continue to explore galaxies(银河系)，space and the solar system to understand how black holes. It is possible that black holes can exist for millions of years，and later contribute further process in galaxies，which can eventually lead to creation of new entities. Scientists also credit black holes as helpful in learning how galaxies began to form.
A. What happens to the objects around a black hole? B. Is there proof that black holes really exist? C. How were black holes named?
D. What are different types of black holes? E. What are black holes made of? F. How are black holes formed? 23. Paragraph 1 F 24. Paragraph 2 E 25. Paragraph 3 A 26. Paragraph 4 B
27. Black holes are formed after___D______.
28. When a large star explodes, the gravity compacts every piece into____F_____ .
29. A newly formed black hole and the star it comes from are of ___C______ .
30. Albert Einstein’s theory of relativity helps to prove____A_____ . A. the existence of black holes B. the creation of new entities C. the same amount of mass D. an explosion of huge stars E. a fraction of an inch F. the tiniest particle 参考答案：FEABDFCA
第4部分：阅读理解(第31~45题，每题3分，共45分)下面有3篇短文，每篇短文后有5道题。
第一篇 Energy and Public Lands
The United States boasts substantial energy resources. Federal lands provide a good deal of US energy production，the US Department of the Interior manages federal energy leasing(租赁)，both on land and on the offshore Outer Continental Shelf。 Production from these sources amounts to nearly 30 percent of total annual US energy production.
In 2000，32 percent of US oil，35 percent of natural gas，and 37 percent of coal were produced from federal lands，representing 20,000 producing oil and gas leases and 135 producing coal leases. Federal lands are also estimated to contain approximately 68 percent of all undiscovered US oil reserves and 74 percent of undiscovered natural gas.
Revenues from federal oil，gas，and coal leasing provide significant returns to US taxpayers as well as State Government. In 1999，for example，$553 million in oil and gas revenues were paid to the US Treasury，and non-India coal leases accounted for over $304 million in revenues，of which 50 percent were paid to State governments. Public lands also play a critical role in energy delivery. Each year，federal land managers authorize rights of way for transmission lines，rail systems，pipelines，and other facilities related to energy production and use. Alternative energy production from federal lands falls behind conventional energy production，though the amount is still significant. For example，federal geothermal(地热)resources produce about 7.5 billion kilowatt-hours(千瓦时)of electricity per year，47 percent of all electricity generated from US geothermal energy. There are 2,960 wind turbines on public lands in California alone，producing electricity for about 300,000 people. Federal hydropower facilities produce about 17 percent of all hydropower produced in the United States.
Because of the growing US thirst for energy and increasing public unease with influence on foreign off sources，pressure on public lands to meet US energy demand is becoming more intense. Public lands are available for energy development only after they have been evaluated through the land use planning process. If development of energy resources conflicts with management or use of other resources，development restrictions or impact moderation measures may be enforced，or mineral be banned altogether. 31. What is the main idea of this passage?
A Public lands are one of the main sources of revenues. B Public lands play an important role in energy production. C Public lands should be developed to ease energy shortage. D Public lands store huge energy resources for further development. 32. Which of the following statements is true of public lands in the U.S.?
A The majority of undiscovered natural gas is stored there. B Half of US energy is produced there.
C Most of coal was produced from there in 2000. D Most energy resources are reserved there.
33. Geothermal resources，wind turbines，and hydropower facilities in Paragraph 4 cited as examples to illustrate that
2013年职称英语考试理工类B级真题及参考答案
