| A.caused widespread damage in the countryside |
| B.affected the entire eastern half of the United States |
| C.almost brought worldwide effect |
| D.existed merely in urban and industrial areas |
| A.shares the same view with the scientists |
| B.is uncertain of its consequence |
| C.rejects it as being ungrounded |
| D.thinks that it will increasingly destroy the world |
| A.raising the world’s temperature a little would not do much harm to life on earth |
| B.lowering the world’s temperature a little would lead to agricultural disasters |
| C.almost no temperature changes have occurred over the past decade |
| D.the world’s temperature will remain constant in the years to come |
| A.the greenhouse effect in the world |
| B.the measures to adjust the climate |
| C.the potential effect of air pollution |
| D.the measures to protect the environment |