—May I speak to your manager Mr.Williams at five o’clock tonight? —I’m sorry. Mr. Williams ________ to a conference long before then.

As the war in Libya goes on, an increasing number of people in the country         from their homes and         a safe place to stay. 

—When did the computer crash?—This morning，while I ________ the reading materials downloaded from some websites.(2012·福建)

After the class，the students went out of the classroom one by one, but only Mary______.　　

–Has your father returned from Africa yet? –Yes, but he _____here for only three days before his company sent him to Australia.