—May I speak to your manager Mr.Williams at five o’clock tonight?—I’m sorry. Mr. Williams

问题补充：

—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

答案：

(答案→)A. will have gone

B. had gone

C. would have gone

D. has gone

解析：考查时态。then指代at five o’clock，由语境可知是将来时间。将来完成时表示将来某时之间或某动作之前已经完成的动作。