It ________be the vocabulary that caused you the problem in the exercise because you know a lot of words.                                                  

I was really anxious about you. You _______ home without a word．

— I think the man over there must be Bob.— It _______ be him. He has gone to England.

We can eat in the dining hall. But we _______ eat in the classroom.

--How about the film last night?  ---We _________ expect a better one. This is the best one that has impressed us that much.