-Tom, you are so lazy．You ought to have finished the work hours ago．-Sorry, I know it ________．A.should beB.must have beenC.ought to have doneD.should have been
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D解析该题为虚拟语气结构，表示与过去事实相反，意为该完成却未完成，含有自我责备之意。选项A为陈述结构；选项B(“一定……”)不符句意；选项C为主动结构，故只有D项才符合句意及其结构。