----- Perhaps John’s not in.

-----_______. Look, the light’s on.

A．Yes, he can be at home.

B．No, he couldn’t go out.

C．Yes, he must be at home.

D．No, he needn’t go out.

下列装置中，（）不属于起重机的安全保护装置。

A.制动装置

B.力矩限制器

C.防滑装置

D.行程限制器