--Listen! Tom is singing in the next room.--It _______ be Tom. He has gone to Shanghai. 

It’s time _____ class. You must _____ the classroom.

－ Look! Mrs Green is wearing a black dress today.－ I think she _______ wear red. She looks young in red.

I _____ have watched that movie --- it’ll give me horrible dreams.

There ________ be any difficulty about passing the road test since you have practised a lot in the driving school.