The textbooks ________ for teaching English as a foreign language came out in the 16th century.
—What has made him upset recently? —_______ alone to face a troublesome milk case.
—What are you doing, John? Why stop? —To be on the safe side, we’d fill up the car now for we _______ run out of gas on the way.
When he realized the police had spotted him, the man _______the exit as quickly as possible.
Bill Gates has created a wonderful “window” ______ people can surf the Internet freely.
—Where is Tom? —Well, he______ you_______ here.Otherwise he would come down right now.