当n=5时，可以容纳的电子总数为（）。
A.18
B.32
C.50
D.72
参考答案：C
They will fly to Shanghai, _____ they plan to stay for two days.
A．when
B．which
C．where
D．why
This is the very reason ______ he gave for his coming late to the meeting.
A．that
C．as
