Of the making of good books there is no end; neither ______ any end to their influence man’s lives.

The question that puzzled them is ____ they can get rid of the air pollution in the area.

It’s clever _____you to help me work out the difficult math problem. Thanks!— You are welcome. Now it’s easier _______you to understand it.

It is _____ that Professor Smith will give us a lecture tomorrow.

Where is mother? —She is in the kitchenShe ___ the dinner for the party the whole afternoon