What about the pen you bought yesterday.– It well. I like it very much.

_____ the chapter four times, and Ifinally understand the author’s theory

Beijing ______a lot in the past ten years. Now it hasbecome one of the biggest modern______ in the world.

Last term our maths teacher set so difficult an examination problem _____ none of us worked out.

We will see you again next Saturday. ______, you must rest as much as possible and take good care of yourself．