问题补充:
Mr. Bo for half a month. He’ll come back in two months.
A. left
B. leave
C. has left
D. has been away
答案:
A. left
B. leave
C. has left
(答案→)D. has been away
解析:句意:Bo先生已经离开了半个月了,两个月之后他将回来。句中有表一段时间的状语for half a month,谓语动词要有延续性,leave 改为be away,故选D.