1. As pointed out at the beginning of the passage, people used to think that air pollution ________.
A. caused widespread damage in the countryside
B. affected the entire eastern half of the United States
C. had damaging effects on health
D. existed merely in urban and industrial areas
2. As far as the greenhouse effect is concerned, the author _____________.
A. shares the same view with the scientists
B. is uncertain of its occurrence
C. rejects it as being ungrounded
D. thinks that it will destroy the world soon
3. The word ′offset′ in the 2nd paragraph could best be replaced by
A. slip into
B. make up for
C. set up
D. catch up with
4. It can be inferred from the passage that
A. raising the world′s temperature only a few degrees would not do much harm to life on the earth
B. lowering the world′s temperature merely a few degrees would lead many major farming areas to disaster
C. almost no temperature variations have occurred over the past decade
D. the world′s temperature will remain constant in the years to come
5. This passage is primarily concerned with
A. the greenhouse effect
B. the burning of fossil fuels
C. the potential effect of air pollution
D. the likelihood of a new ice age
