A. 导线和绝缘子 B. 绝缘子与绝缘子 C. 避雷线和导线 D. 绝缘子与杆塔
A. when it is not under strain B. if both ends are made fast C. in an emergency D. at no time
A. 1435mm B. 1353mm C. 1433mm D. 1432mm