进入无人操控电梯，陪同人员应该（）
A.请客人先进入并操控电梯
B.自己先进入并操控电梯
C.谁方便谁先进入电梯
参考答案：B
I don't know what happened _____ Zhang Hong the day before yesterday. [ ]
A. at
B. for
C. about
D. to
