1 . Bicycling is good exercise; ______, does not pollute the air. （用适当的词填空）

2 . He learned English by ______ (listen) to the radio. (所给词的适当形式填空）

3 . His wish is ______ (become) an astronaut. (所给词的适当形式填空）

4 . There______(be)a fair amount of traffic on the roads.(所给词的适当形式填空)

5 . I was suddenly seized ______ a feeling of great insecurity and loneliness. (用适当的词填空)

6 . See, your computer has broken down again！It doesn’t make sense ______（buy）the cheapest brand of computer just to save a few dollars. （用所给单词适当形式填空）

7 . At present, __________ (billion) of people live without sufficient shelter and clean water. (所给词的适当形式填空）

8 . We’re going to be meeting there on a regular _________(base). (所给词的适当形式填空）

9 . You can get burned________a variety________ things：hot liquids，steam，fire，radiation，the sun，electricity and chemicals. (用适当的词填空)

10 . Why are shameless and shameful ________(behave) the same?（所给词的适当形式填空）