.I didn’t see Mr White at the meeting . he come he would have given a lecture.A. WouldB.

问题补充：

.I didn’t see Mr White at the meeting . he come, he would have given a lecture.

A. Would

B. Did

C. Should

D. Had

答案：

A. Would

B. Did

C. Should

(答案→)D. Had

解析：根据语境可知, 后一句是一个表示与过去事实相反的假设。if条件从句用过去完成时had done主句用would have+ 过去分词, 又知if条件句中如有were, should, had，可以省去if，并使用倒装语序, 即were, should, had+主语+谓语动词。故答案为D。