练习：
1. According to the first two paragraphs，the author thinks that
A strong measures have been taken by the government to prevent global warming.
B to reduce carbon emissions is all impossible mission.
C despite the difficulty，scientists have some options to prevent global warming.
D actions suggested by scientists will never be realized.
2. Scientists resist talking about their options because they dont want people to
A know what they are doing.
B feel their efforts are useless.
C think the problem has been solved.
D see the real problem.
3. What does Stephen Schneider say about a heroin addict and methadone？
A Methadone is an effective way to treat a hard heroin addict.
B Methadone is not a correct way to treat a heroin addict.
C Hospitalization together with methadone can work effectively with a heroin addict.
D Methadone and heroin are equally effective in treating a heroin addict.
4. What is Stephen Schneider‘s idea of preventing global warming？
A To ask governments to take stronger measures;
B To increase the sunlight reaching the Earth.
C To apply sunscreen to the Earth.
D To decrease greenhouse gases.
5. What is NOT true of the effectiveness of “sunscreen”，according to the last paragraph？
A It deflects sunlight reaching the Earth to counteract the warming.
B It blocks the incident energy in the sun‘s rays.
C It is a controversial method.
D It decreases greenhouse gases in the atmosphere.
答案与题解：
1. C 短文第一段讲了防止地球变暖是一项艰巨的任务，第二段说，尽管如此，科学家还是有一些办法，所以C是正确选择。A是错误选择，因为作者认为政府和一些利益集团阻碍了科学家所倡导的行动的实施；B不是作者的观点；D也不是正确选择，因为第一段的最后一句“might not be implemented soon enough”并不表明永远不能实现。
2. C 文章的第二段说，即使最糟糕的情况发生，科学家还是有几招的。但他们不希望讨论他们的招数，因为恐怕人们不再有危机感而削弱彻底解决问题的努力。所以C是正确选择。
3. A 文章的第二段中，Stephen Schneider教授将自己解决地球变暖问题的办法比作美沙酮，因为在瘾君子拒绝正常住院治疗时，服用美沙酮是一种缓解海洛因毒瘾的有效方法。所以，A是正确的选择。
4. C 文章最后一段的第一个句子提供的答案。
5. D 短文最后一段描述了“sunscreen”如何解决地球变暖问题。尽管有争议，但是研究证明，“太阳屏”能反射和阻碍阳光，起到抵消由温室效应引起的地球升温。最后一段的第三和第四句是理解这个问题的关键。D不是文章所表达的内。容，所以是正确答案。