16．He is sitting ____ the front of the car.

15．What are you talking ____ ?

14．Ducks are good ____ swimming.

13．What's the time? It's half ____ seven.

12．I have quite a lot ____ homework to do.

11．It's time ____ school.

10．I often help my mother ____ _ the housework.

9．Don't sleep ____ the open air.

8．May I borrow a pencil ____ you?

7．I was born ____ July 1, 1982.