It was the third time that I _______of the changes of the timetable.

A．had informed

B．has informed

C．had been informed

D．has been informed

使用卷扬机作业前应进行检查和试车，确认卷扬机设置稳固，（）、保险棘轮、索具等合格后方可使用。

A.防护设施

B.电气绝缘

C.制动装置

D.导向滑轮