【题目】I______ thank you too much for all your help to my son while we were away from home.
A.won't
B.can't
C.can
D.will

【答案】B
【解析】句意：对于我不在家时，你对我儿子的帮助，我怎么感谢你也不为过。所填情态动词与too 构成固定句型can't/couldn't …too…，意思是：再……都不为过，选B。