E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
2. Paragraph4 __
(Hansen found soot’s effect on snow albedo (solar energy reflected back to space)，which may be contributing to trends toward early springs in the Northern Hemisphere，such as thinning Arctic sea ice，melting glaciers and permafrost)。Soot also is believed to play a role in changes in the atmosphere above the oceans and land.
2.A.分析：因为段落中soot出现了两次，因此重点注意包含soot的被选项： A和E，同样段落中没有提到有关“煤灰散发”的问题，所以判断A是答案(段落最后一句(观点句)的含义与A一致)
提示：“避重就轻法”—段首句复杂则看段未句。
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo (反照率)
E Ways to Reduce Soot Emission
F Greenhouse Gases as the Main Factor of G1obal Warming
3. Paragraph 6 __。
Hansen cautioned，although the role of soot in altering global climate is substantial，it does not alter the fact that greenhouse gases are the primary cause of climate warming during the past century.Such gases are expected to be the largest climate forcing for the rest of this century.
3. F. 分析：因为段落中gas出现了两次，因此重点注意包含gas的被选项：F.而F中的内容正好与段首句中的核心结构(it does not alter the fact that greenhouse gases are the primary cause of climate warming during the past century(它没有改变‘温室效应是在过去的世纪中造成气候变暖的主要原因’这个事实))一致。
B Observations of Warming in the Northern Hemisphere
C Effect to Reduce Snow Albedo (反照率)
E Ways to Reduce Soot Emission
4.Paragraph 7 __。
The researchers found that observed warming in the Northern Hemisphere was large in the winter and spring at middle and high latitudes.(These observations were consistent with the researchers’climate model simulations， which showed some of the 1argest warming effects occurred when there were heavy snow cover and sufficient sunlight.)
4. B.分析：段首句中出现了Northern Hemisphere，而接下来的句子中出现了“These observations”，这些词都被包含在B中，因此判断B是答案。
A produces much more global warming than a carbon-dioxide forcing of the same magnitude
B contributed to 25 percent of observed global warming
C can produce greenhouse gases