题目分析

1. 答案为D，属猜词题。从句子"it appears that increased air pollution during those 30 years - over Asia, in particular - with the help, perhaps, of some increased cloudiness, may have exerted a cooling influence on the surface of the planet even as carbon dioxide and other greenhouse gases were encouraging the atmosphere to warm."我们可看出一方面空气污染物及其形成的云星对地球表面有一种冷却作用，另一方面二氧化碳和其它温室气体却促使大气变暖。这是一种相互作用，一方强，另一方就弱，就像是"拔河赛"。文章最后一段的一句话"They are just beginning to grapple with the problem of how global warming and solar dimming interact."可以进一步印证我们的这一判断。

2. 答案为A，属情感态度。原文对应信息是"no task could be more urgent"。注意含有比较级的否定式的理解，这句话的意思是"This task is the most urgent."从这句话我们可看出气候学家们对待此事的态度。

3. 答案为B，属推理判断题。文章最后一段的中心思想是：对太阳变暗这一问题的研究还只是刚刚开始，还有很多东西我们不了解。然欧以拉曼纳森（Ramanathan）的话结束全文。就此我们可以判断拉曼纳森的话也应该是符合这段文章的中心大意的。

4．答案为A，属事实细节题。原文对应信息是"it appears that increased air pollution during those 30 year - over Asia, in particular - with the help, perhaps, of some increased cloudiness, may have exerted a cooling influence on the surface of the planet"。这句话的意思是"全球--特别是亚洲--不断加剧的大气污染，借助数量有所增加的云度可能对整个地球表面起了一种冷却作用"，而在形成云层的过程中由于"the cloud droplets that form are too small and never become weighty enough to fall to the ground"（所形成的云状水滴显得又太小，永远达不到足以落到地面的重量），所以这些云层无法变成雨滴落在地面，而是停留在大气层，从而对大气层起到一种冷却作用。选项A是这种现象所造成的结果。

5．答案为C，属推理判断题。文章最后一段提出对太阳变暗这一问题的研究还只是刚刚开始，还有很多东西我们不了解。由此我们可做出判断。