I can’t thank you too much for your kindness because without your help Ihave won the first

问题补充：

I can’t thank you too much for your kindness because without your help Ihave won the first prize in the speech contest．

A. can’t

B. shouldn’t

C. might not

D. couldn’t

答案：

A. can’t

B. shouldn’t

C. might not

(答案→)D. couldn’t

解析：考查情态动词的虚拟语气的用法。意为，我再感谢你也不为过，没有你的帮助，我不可能在演讲比赛中获得第一名。根据句意可知，演讲比赛已经结束。Can have done 不可能做了某事。 Shouldn have done 本不应当做某事 might not have done 可能没有干某事，均不符合题意。