调相机的主要用途是供给()、改善功率因数、调整网络电压,对改善电力系统运行的稳定性起一定的作用。
A.有功功率
B.无功功率
C.有功功率和无功功率
D.视在功率
参考答案:B
奇数之和整数的平方叫做什么数()
A、正方形数
B、长方形数
C、正三角形数
D、三角形数
A.Washington, Adams arid Jefferson are most famous in the history of the United States.
B.Washington, Adams and Jefferson had many different interests.
C.Washington, Adams and Jefferson returned home after they were retired.
D.Washington, Adams and Jefferson were the first three Presidents.