单句语法填空。

1. By the time he got home, his wife ______ (do) all the housework.

2. In the United States, lunch _______ (offer) to students for free at school.

3. The first step towards _______ (protect) the environment is to live a "low-carbon" lifestyle.

4. While I ______ (sweep) the floor yesterday, the telephone rang.

5. The audience are requested _______ (show) their tickets when they enter the cinema.

6. They _______ (eat) up all the food, but they still feel hungry.

7. We meet each other _______ (frequent) in this hotel.

8. I prefer basketball _______ football.

9. By reading we can ________ (rich) our vocabulary and improve our English.

10. My friend is growing _______ tired of English words that he wants to give it up.