The teacher ____ have thought John was worth it or she wouldn't have wasted time on him.

问题描述:

The teacher ____ have thought John was worth it or she wouldn't have wasted time on him.
A.should B.can C.would D.must
我知道B肯定不对的,然后我觉得A代进去更加通顺,为什么不选A呢?

如果是A的话,should have thought ,是本应该认为却没有认为.而把D带入其中的意思就是带有肯定语气的推测,老师一定是认为……
所以应该选D而非A