程控制网由沿水准路线按一定的距离埋设的固定标志即水准点构成。
参考答案：对
If an oligopoly is characterized by fierce competition, in long-run equilibrium the firms in the market will earn:（）
A. zero economic profits.
B. substantial economic losses.
C. substantial economic profits.
感应耐压试验方法有（）感应耐压试验两种.
A.工频、中频
B.工频、高频
C.冲击波、高频
D.冲击波、工频
