220kV串联补偿装置红外热像检测基准周期为()
A.3月
B.6月
C.9月
D.12月
参考答案:A
We are not permitted ________ mobile phones to school. [ ]
A. taking
B. to take
C. take
D. taken
离心式压缩机转子的叶轮按锻造工艺有几种类型?