---What do you think is the matter with your car? ---Well, it _____ start at all. I mean I turned the key and nothing happened. 

Four hundred dollars for just a pair of shoes? You ______ be joking!

I______ thank you too much for all your help to my son while we were away from home.

---Do you know how this disabled man succeeded in running such a big company?--- I don’t know , but I think he __________ many difficulties.

A good rest between classes ________ recover brain power to its best and make us perform better in class later.