阅读理解
下面有一篇短文，每篇短文后有5道题。请根据短文内容，为每题确定1个最佳选项。
A Sunshade for the Planet
Even with the best will1 in the world，reducing our carbon emissions is not going to prevent global warming.It has become clear that even if we take the most strong measures to control emissions，the uncertainties in our climate models still lea'ye open the possibility of extreme warming and rises in sea level.At the same time，resistance by governments and special interest groups makes it quite possible that the actions suggested by climate scientists might not be implemented soon enough.
Fortunately，if the worst comes to the worst2，scientists still have a few tricks up their sleeves3.For the most part they have strongly resisted discussing these options for fear of inviting a sense of complacency that might thwart efforts to tackle the root of the problem.Until now，that is.A growing number of researchers are taking a fresh look at large-scale “geoengineering” projects that might be used to counteract global warming.“I use the analogy of methadone4,” says Stephen Schneider，a climate researcher at Stanford University in California who was among the first to draw attention to global warming.“If you have a heroin addict，the correct treatment is hospitalization，and a long rehab. But if they absolutely refuse，methadone is better than heroin.”
Basically the idea is to apply “sunscreen” to the whole planet.One astronomer has come up with a radical plan to cool Earth;launch trillions of feather-light discs into space，where they would form a vast cloud that would block the sun’s rays.It’s controversial，but recent studies suggest there are ways to deflect just enough of the sunlight reaching the Earth’s surface to counteract the warming produced by the greenhouse effect.Global climate models show that blocking just 1.8 per cent of the incident energy in the sun’s rays would cancel out the warming effects produced by a doubling of greenhouse gases in the atmosphere. That could be crucial，because even the most severe emissions-control measures being proposed would leave us with a doubling of carbon dioxide by the end of this century，and that would last for at least a century more.
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 don't 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.
