3.　　　 在it后加was

2.　　　 去掉a

1.　　　 being改为be

30. ----May I go and play with Tom this afternoon, Mum?

----No. You can't go out _____ your homework is being done.

29. We have reached the point _____ a change is needed.

A. which B. when C. that D. where

28. ----Did you give him the book?

----Yes. I gave it to him _______ I saw him.

A. once B. hurriedly C. while D. directly

27. ----which one can I take?

----You can take ______ of them; I'll keep none.

A. both B. any C. neither D. all

26. The boss _________ 30 dollars from my salary without any good reason.

A. brought down B. kept back C. cut off D. held up

25. I kept this picture _____ I can see it every day as it reminds me of my university days.

A. in which B. where C. when D. whether

24. ----Have you seen _____ pen? I left it here this morning.

----Is it ____ black one? I think I saw it somewhere.

A. a, the B. the, the C. the, a D. a, a