单选题 1 There is growing evidence that urbanization has a sharp impact on climate, causing changes that can wreak havoc on precipitation patterns that supply the precious resource of water. The heavy amounts of heat and pollution rising from cities both delay and stimulate the fall of precipitation, depriving some areas of rain while drenching others.
2 Cities are on average one to ten degrees warmer than surrounding undeveloped areas. Cities also produce large amounts of pollutants called aerosols, gaseous suspensions of dust particles or byproducts from the burning of fossil fuels. Both heat and aerosols change the dynamics of clouds. When hoisted up in the sky, the microscopic particles act as multiple surfaces on which the moisture in clouds can condense as tiny droplets. This can prevent or delay the formation of larger raindrops that fall more easily from the sky, or it can cause the rain to fall in another location.
3 In California, pollution blows eastward and causes a precipitation shortage of around one trillion gallons a year across the Sierra Nevada mountain range. By contrast, in very humid cities, such as Houston, heat and pollutants seem to invigorate summer storm activity by allowing clouds to build higher and fuller before releasing torrential rains.

单选题 The phrase wreak havoc on in paragraph 1 means
【正确答案】 A
【答案解析】Wreak havoc on means disrupt in this context. Clues: ...has a sharp impact on...; ...changes that can---precipitation patterns...; ... both delay and stimulate the fall of precipitation
单选题 The word drenching in paragraph 1 is closest in meaning to
【正确答案】 C
【答案解析】Drenching means thoroughly wetting in this context. Clues: ... both delay and stimulate the fall of precipitation, depriving some areas of rain while others. While shows contrast between depriving some areas of rain and drenching.
单选题 The word hoisted in paragraph 2 is closest in meaning to
【正确答案】 A
【答案解析】Hoisted means lifted in this context. Clues: ...heavy amounts of heat and pollution rising from cities...; ... up in the sky
单选题 The word torrential in paragraph 3 is closest in meaning to
【正确答案】 D
【答案解析】Torrential means heavy in this context. Clues: ... a precipitation shortage...; By contrast.., invigorate summer storm activity.., allowing clouds to build higher and fuller By contrast shows contrast between precipitation shortage and torrential rains.