---The book is borrowed from the library. You your children touch it with their dirty han

---The book is borrowed from the library. You your children touch it with their dirty hands.
　---Sorry.　
A. should have let　
B. needn’t have let　
C. mustn’t have let
D. ought not to have let

A. should have let　B. needn’t have let　C. mustn’t have let(答案→)D. ought not to have let解析：考查情态动词。ought not to have done本不应当做某事。句意：——书借自图书馆，你本不应当让孩子用脏手碰它。——对不起。

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