通常说的无功电力指的是()。
A、感性电流
B、容性电流
C、瞬时功率
D、无功功率
参考答案:D
He hasn’t slept at all for three days.____he is tired out.
A.It is no wonder
B.There is no need
C.There is no point
D.It is no way
扣模的种类分为()、()和连续扣模。