正弦交流电路分别用P表示有功功率,Q表示无功功率,S表示视在功率,则功率因素可表示为()。
A.P/Q
B.P/S
C.Q/S
D.Q/P
参考答案:B
—Clean-up Day is only two weeks from now. How should we make more people know it?
—We could ______ advertisements after school. [ ]
A. call up
B. hand out
C. put off
D. think up
牙齿燥如枯骨多为()
A.阳明热盛津液大伤
B.肾阴枯竭精不上荣
C.肾阴不足虚火上炎
D.胃阴损伤
E.湿热蕴脾