He is ____  as a leader but he hasn't ____ inteaching.    [ ]

A. success; many experiences    

B. a success; much experience    

C. great success; an experience    

D. a great success; any experiences

轿厢顶部装防护栏杆是为了（）.

A.轿厢冲顶时，不会使轿厢顶部撞到井道顶部的楼板

B.防止检修人员踏空坠落底坑

C.电梯中途停车，司机从轿顶撤出时起到安全保护作用

D.电梯中途停车，乘客从轿项撤出时起到安全保护作用