在二极管桥式整流电容滤波电路中,若有一个二极管接反,将造成()。
A.半波整流
B.短路,损坏元件
C.断种,不能工作
D.短路
参考答案:A
阅读短文,选择正确答案。
My father has a good friend in his factory. He's an old man. All of the children like him. We call him Uncle
Mike. He is from Canada. He lives in Beijing. He can't speak Chinese. We teach him Chinese. He teaches us
English. He doesn't work on Sundays. Look! He's mending (修理) a kite at home. He likes watching TV with hisson and daughter in the evening.
1. Uncle Mike and my father work in the same .[ ]
A. farm
B. school
C. factory
2. Uncle Mike comes from .[ ]
A. Canada
B. China
C. England
3. We teach Uncle Mike .[ ]
A. English
B. Japanese (日语)
C. Chinese
4. Uncle Mike likes . [ ]
A. mending a kite
B. watching TV
C. drawing
5. Uncle Mike's good friend.[ ]
A. I am
B. My father is
C. My mother is
下列施工不属于临近营业线B类施工的是哪一项()
A、营业线路堑地段有可能发生物体坠落,翻落侵入营业线设备安全限界的施工。
B、使用高度或作业半径大于吊车至营业线设备安全限界之间距离的吊车吊装作业。
C、邻近营业线进行现浇梁、钢板桩、钢管桩、搭设脚手架、膺架等施工的设备和材料翻落后侵入营业线设备安全限界的施工。
D、邻近铁路营业线进行影响营业线设备稳定、使用和行车安全的工程施工。