判断图22中电流表的读值（）。
A．2A
B．4A
C．6A
D．8A
参考答案：B
解析：
以电压为参考相量画电流的相量图，可求得。
在等比数列{an}中，a1+a5=82，a2•a4=81，则a3=______．
―What do you think of this dress, darling?
―Er...sorry, dear. I _______. What did you say?
A．didn't listen
B．hadn't listened
C．haven't listened
D．wasn't listening
