题目内容
—You________ Mary yesterday,Peter.?
—Sorry,but I was too busy to do that.?
A.must have helped?
B.should help?
C.were supposed to have helped?
D.were able to help?
C
根据语境,彼德过去应该帮助Mary,但是没有,所以可以排除B、D两项。而A项是对过去所发生事情的猜测,不符合题意。be supposed to do 意为“理应,本该”,用法类似should,可用于虚拟语气中。
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