[单项选择]Air pollution, together with overpopulation, ____ many problems in big cities.
A. are causing
B. is causing
C. are caused
D. is caused

[单项选择]Neighboring landholders: Air pollution from the giant aluminum refinery that has been built next to our land is killing our plants. Company spokesperson: The refinery is not to blame, since our study shows that the damage is due to insects and fungi. Which of the following, if true, most seriously weakens the conclusion drawn by the company spokesperson
A. The study did not measure the quantity of pollutants emitted into the surrounding air by the aluminum refinery
B. The neighboring landholders have made no change in the way they take care of their plants
C. Air pollution from the refinery has changed the chemical balance in the plants" environment, allowing the harmful insects and fungi to thrive
D. Pollutants that are invisible and odorless are emitted into the surrounding air by the refinery
E. The various species of insects and fungi mentioned in the study have been occasionally found in the locality during the past hundred years

[单项选择]

Scientists claim that air pollution causes a decline in the world’ s average air temperature. In order to prove that theory, ecologists have turned to historical data in relation to especially huge volcanic eruptions. They suspect that volcanoes effect weather changes that are similar to air pollution.
One source of information is the effect of the eruption of Tambora, a volcano in Sumbawa, the Dutch East Indies ( the former name of the Republic of Indonesia) ,in April 1815. The largest recorded volcanic eruption, Tambora threw 150 million ton of fine ash into the stratosphere. The ash from a volcano spreads worldwide in a few days and remains in the air for years. Its effect is to turn in coming solar radiation into space and thus cool the earth. For example, records of weather in Eng land show that between April and November 1815, the average temperature had fallen 4.5°F during the next twenty-four months, England suffered one of the coldest periods of its his
A. of several days’ duration worldwide
B. felt mainly in the Dutch East Indies
C. evident in the decreased world temperature
D. immediately evident to the world’s scientists

[单项选择]

There was one thought that air pollution affected only the area immediately around large cities with factories and heavy automobile traffic. At present, we realize that although these are the areas with the worst air pollution, the problem is literally worldwide. On several occasions over the past decade, a heavy cloud of air pollution has covered the east of the United States and brought health warnings in rural areas away from any major concentration of manufacturing and automobile traffic. In fact, the very climate of the entire earth may be infected by air pollution. Some scientists consider that the increasing concentration of carbon dioxide in the air resulting from the burning of fossil fuels (coal and oil)is creating a "greenhouse effect" —conserving heat reflected from the earth and raising the world’s average temperature. If this view is correct and the world’s temperature is raised only a few degrees, much of the polar ice cap will melt and
A. caused widespread damage in the countryside
B. affected the entire eastern half of the United States
C. had damaged effect on health
D. existed merely in urban and industries areas

[单项选择]　　There was one thought that air pollution affected only the area immediately around large cities with factories and heavy automobile traffic. At present, we realize that although these are the areas with the worst air pollution, the problem is literally worldwide. On several occasions over the past decade, a heavy cloud of air pollution has covered the east of the United States and brought health warnings in rural areas away from any major concentration of manufacturing and automobile traffic. In fact, the very climate of the entire earth may be infected by air pollution. Some scientists consider that the increasing concentration of carbon dioxide in the air resulting from the burning of fossil fuels (coal and oil)is creating a "greenhouse effect" ― conserving heat reflected from the earth and raising the world’’ s average temperature. If this view is correct and the world’’ s temperature is raised only a few degrees, much of the polar ice cap will melt and cities such as New York, Bo
A. slip into
B. make up for
C. set up
D. catch up with