2. 考研
  3. In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list (A、B、C、

In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list (A、B、C、

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问题 In the following text, some sentences have been removed. For Questions 41-45, choose the most suitable one from the list (A、B、C、D、E、F、G……) to fit into each of the numbered blank. There are several extra choices, which do not fit in any of the gaps. (10 points)

    A significant portion of industry and transportation burns fossil fuels, such as gasoline. When these fuels burn, chemicals and particulate matter are released into the atmosphere. Although a vast number of substances contribute to air pollution, the most common air pollutants contain carbon, sulfur, and nitrogen.
    (41)______.
    Acid rain forms when sulfur dioxide and nitrous oxide transform into sulfuric acid and nitric acid in the atmosphere and come back to Earth in precipitation. Acid rain has made numerous lakes so acidic that they no longer support fish populations.
    (42)______.
    Estimates suggest that nearly 1.5 billion people worldwide lack safe drinking water and that at least 5 million deaths per year can be attributed to waterborne diseases. Water pollution may come from point sources or nonpoint sources. Point sources discharge pollutants from specific locations, such as factories, sewage treatment plants, and oil tankers. The technology exists to monitor and regulate point sources of pollution, although in some areas this occurs only sporadically. Pollution from nonpoint sources occurs when rainfall or snowmelt moves over and through the ground.
    (43)______.
    With almost 80 percent of the planet covered by oceans, people have long acted as if those bodies of water could serve as a limitless dumping ground for wastes. However, raw sewage, garbage, and oil spills have begun to overwhelm the diluting capabilities of the oceans, and most coastal waters are now polluted, threatening marine wildlife.
    (44)______.
    Water that collects beneath the ground is called groundwater. Worldwide, groundwater is 40 times more abundant than fresh water in streams and lakes. In the United States, approximately half the drinking water comes from groundwater. Although groundwater is a renewable resource, reserves replenish relatively slowly. Presently, groundwater in the United States is withdrawn approximately 4 times faster than it is naturally replaced. (45)______.

A. Beaches around the world close regularly, often because the surrounding waters contain high levels of bacteria from sewage disposal.
B. These chemicals interact with one another and with ultraviolet radiation in sunlight in dangerous ways. Smog, usually found in urban areas with large numbers of automobiles, forms when nitrogen oxides react with hydrocarbons in the air to produce aldehydes and ketones. Smog can cause serious health problems.
C. Acid rain is also responsible for the decline of many forest ecosystems worldwide, including Germany’s Black Forest and forests throughout the eastern United States.
D. In addition to groundwater depletion, scientists worry about groundwater contamination, which arises from leaking underground storage tanks, poorly designed industrial waste ponds, and seepage from the deep-well injection of hazardous wastes into underground geologic formations.
E. The Ogallala Aquifer, a huge underground reservoir stretching under eight states of the Great Plains, is drawn down at rates exceeding 100 times the replacement rate. Agricultural practices depending on this source of water need to change within a generation in order to save this groundwater source.
F. As the runoff moves, it picks up and carries away pollutants, such as pesticides and fertilizers, depositing the pollutants into lakes, rivers, wetlands, coastal waters, and even underground sources of drinking water. Pollution arising from nonpoint sources accounts for a majority of the contaminants in streams and lakes.
G. By some estimates, on average, 25 percent of usable groundwater is contaminated, and in some areas as much as 75 percent is contaminated.
选项
答案B
解析 文章第1段提到大量的工业生产和交通工具燃烧石油，形成空气中的碳、硫、氮等污染物。B的第1句正好衔接第1段的内容：这些化合物相互作用，以各种危险的方式与阳光中的紫外线辐射起作用。
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