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

1. A.
   should have let　
2. B.
   needn’t have let　
3. C.
   mustn’t have let
4. D.
   ought not to have let

---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

---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