单选题 "May I speak to your manager Mr. Williams at five o'clock tonight? I'm sorry. Mr. Williams ______ to a conference long before then. "
A. will have gone B. had gone C. would have gone D. has gone

【正确答案】 A

【答案解析】[解析] 根据题意，可见before then相当于before five o’clock tonight，表示的是在将来某个时间之前要完成的动作，因此，此处谓语动词要使用将来完成时。Mr．williams is going to attend the meeting at 11 o’clock．Before then he will have prepared his address．威廉姆斯先生要在11点出席会议，在此之前他要把讲稿准备好。