—Who______ it be that is knocking at the door?  
—It ______ be Father, but I’m not sure.

—I want to know if I__________ smoke here.
—No, you _________.Could you see the sign “NO SMOKING” there?

13. There________be any difficulty in passing the road test Since you have practiced a lot in the driving school.

9．If you __________talk about it with me, please wait till I finish my work at hand.

32. -- I didn’t go to the movie last night because of the rain.
-- What a pity! If I had got the ticket, I    it.

30. -- Why    you be talking so loudly while others are studying?
-- I am terribly sorry.

27.---Where have you been?  
---I got caught in traffic, otherwise I _______ here earlier.

27. ----Can I catch a train to Beijing?
----You _____miss one. There are many trains to Beijing.

30. He _____ his potential had it not been for his desire to meet new challenges.

33．Just as I was sitting down to supper, the telephone______.