电梯出现关人现象，维修人员首先应做的是（）。

A.打开抱闸，盘车放人

B.切断电梯动力电源

C.与轿内人员取得联系

D.打开厅门放人

At the evening party the host said ______ was able to solve the riddle could get a nice present as a

reward.[ ]

A. whoever  

B. who        

C. no matter who

D. whomever