【题目】By the end of last week,600 people from 50 countries to attend the meeting，with nearly half coming from the United States，Germany and Britain.
A. had registered B. have registered
C. registered D. were registered
在线课程【答案】A
【解析】考查时态。根据时间状语by the end of last week表示谓语动词动作发生在“过去的过去”，所以用过去完成时。