The teacher have thought Johnson was worth it or she wouldn’t have wasted time on him,I suppose.
A. should
B. can
C. would
D. must
网友回答
A. should
B. can
C. would
(答案→)D. must
解析：“must have +动词+ed形式”表示“一定做了某事”。根据所提供的情景or she wouldn’t have wasted time on him可判断出老师一定认为Johnson值得教，要不她不会在他身上浪费那么多时间。“should have +动词+ed形式”表示“本来应该做某事，而没有做”，常用于表示责备。“can have +动词+ed形式”表示“可能做了某事”。would用于表示虚拟、假设、条件等，有“要、将要、会、就会”等意思。