简述感应雷入侵的三种途径。
参考答案:
①雷电的地电位反击电压通过接地体入侵;
②由交流供电电源线路入侵;
③由通信信号线路入侵。
Not ever to “Shanzhamei”, a country girl, that she could be the first runner-up of 2013 on the Avenue of stars, CCTV .
A.it occurred
B.it occurs
C.has it occurred
D.did it occur
建筑材料与装饰材料会把污染物带入公共场所,其中值得注意的是()。
A.甲醛和氨
B.甲醇和氡
C.甲醛和氡
D.甲醇和氨
E.甲醛和镭