题目

______ their homework, these three students have to stay in the classroom for another thirty minutes. A. Not finishing                      B. Not finished C. Having not finished             D. Not having finished 答案：D 解析: 略— Hello, is Billy in? — Sorry, he isn’t in, ____A. Billy, here is a call for you.　　　　　　　　　　 B. can you take a message?C. go ahead, I’ll give him a message.　　　　 D. Billy, get the call.