Peter pulled up his collar so hi

Peter pulled up his collar so high that you（ ） have seen his head from behind if you had been there.
A、wouldn't
B、mustn't
C、couldn't
D、shouldn't
【正确答案】：C
【题目解析】：本句意为Peter把领子拉的很高，即便你在那，从后面也不可能看见他的头。couldn't have done不可能，shouldn't have done 本不应该做却做了，mustn't have done是不存在，couldn't have done才是must have done 的否定形式。wouldn't have done是虚拟语气，指不会这么做。