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

If you are in the zoo, remember not to touch or go near the animals. Although some of the animals are cute, you _________ leave them alone. 

—Peter doesn’t mind lending you his camera.—He __________. I’ve already borrowed one.

— Who has done that again? — _______ you ask? Little Tom, of course!

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