资源介绍：
1. 这套试题考查了puzzle, mass, now that等重点词语以及名词性从句的用法。
2. 阅读理解介绍了美国天文学家Nancy Roman。

1. There _____ a lake on the top of the mountain.
A. have    B. existed      C. lie         D. exist
2. The _____ expression on her face showed that she knew nothing about the truth.
A. puzzled  B. puzzle       C. puzzling    D. to puzzle
3. People in the city are ____ old houses and building new ones.
A. breaking down       B. pulling down
C. putting down        D. burning down
4. There are_____ people in the supermarket during the National Day holidays.
A. a plenty of          B. masses of
 C. a great many of      D. a great amount of