在RL串联电路中，下列功率表达式（）正确。
A.P=I2R；
B.P=V2/R；
C.P=VI；
D.P=U2/Z。
参考答案：A
Here is a survey about hopes and dreams ______ thousands of students took part.
A．at which
B．in which
C．with which
D．about which
You will be late for school _____ you don't hurry. [ ]
A. even
B. that
C. if
D. before
