---Can you tell me something about your school rules?

---Well, We are told ______anywhere. It’s our duty to keep our school clean and tidy.

A．not to make much noise

B．to draw

C．to throw waste paper

D．not to spit

钢丝绳破坏的主要原因是（）。

A.弯曲；

B.疲劳；

C.拉断；

D.压扁;