－Where did you put the car keys? －Oh, I ______ I put them on the chair because the phone rang as I ______ in.

A unique ______ of these rock shelters was that they were dry.

Many people agree that there has never been a more splendid opening ceremony than ______ of the Beijing Olympic Games in history.

It is generally considered unwise to give a child ____ heor she wants

The reason ____ his coming to China is _____ he wants to study in China[ ]