35．Eating too much isn't good ____ your health.

34．I think Mary is ____ duty today.

33．When did you arrive ____ the village?

32．Did you live ____ Beijing in 1997?

31．The eraser was passed ____ one student ____ another.

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

29．What are you talking ____ ?

28．Ducks are good ____ swimming.

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

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