单选题 The conference ______ a full week by the time it ends.
A. must have lasted B. will have lasted
C. would last D. have lasted

【正确答案】 B
【答案解析】[解析] 本题考查谓语动词的时态。由by the time it ends可知谓语动词应用将来完成时表示在将来某一时间已经完成的动作。