Before we did detailed reading, the teacher asked some ______ questions to let us learn about the main idea of the passage.

________ people are concerned about now is the Shanghai World Expo, which ________ start on May 1st

_________ who had arrested him three times for carrying drugs.

He pretended to be a doctor，but ____ he is a cheat

These tickets are useless. Can I –Yes, but make sure you put them in thedustbin.