He must have known the truth yesterday, ?
A. haven’t you
B. didn’t you
C. have you
D. did you
网友回答
A. haven’t you
(答案→)B. didn’t you
C. have you
D. did you
解析：考查反意问句：句意：他昨天一定知道真相了，是吗？前面的简单句是用must have done表示推测，反意问句要根据时间判断，如果有具体的过去时间，就用一般过去式，如果没有具体的过去时间，就用现在完成时，排除AC项，因为前面肯定，所以问句是否定，选B。