Tom,Bob and Betty have arrived, but ___ students haven’t yet.

Larry asks Bill and Peter to go on a picnic with him, but ______ of them wants to, because they have work to do.

 Does ________ matter much if they do not come tomorrow?

 If you don't go after what you want, you will never have ________.

What seems to be a simple idea always turns out _____ that is hard to put into practice．