I ______ to the lecture that afternoon, but I ______ a bit ill.

A.should have gone; was

B.would have gone; had been

C.should go; was

D.would go; had been

答案及解析： A

解析：

考查虚拟语气。根据时间状语that afternoon可知是对过去的情况比赛虚拟，使用情态动词+have done,排除CD。Should have done本应该做某事，实际上却未坐；would have done会做某事。But后面的句子应该使用陈述语序，根据前句的that night可知后半句使用过去时。故A正确。