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【多选题】
指出架空线路导线振动的起因，对线路将会引起（）种事故。A.
架空输电线路的导线（避雷线）受到稳定的微风作用时，在导线背后形成以一定频率上下交替变化的气流旋涡，从而使导线受到一个上下交变的脉冲力作用
B.
导线振动的波形为驻波，即波节不变，波幅上下交替变化，而且一年中导线振动的时间全年时间的20%～30%
C.
导线振动的波形为驻波，即波节不变，波幅上下交替变化，而且一年中导线振动的时间全年时间的30%～50%
D.
无论导线以什么频率振动，线夹出口处总是一波节点，所以，导线振动使导线在线夹出口处反复拗折，引起材料疲劳，最后导致断股、断线事故，对线路的正常安全运行危害较大
E.
当气流旋涡的交替变化频率与导线的固有自振频率不相等时，导线在垂直面内产生共振即引起导线振动
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A.
1.2
B.
1.3
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A.
There was a hole in the door, through which I ____sight of Mr. Brown sitting in a chair. A．caught
B.
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got
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A.
减小液压
B.
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D.
减小液压、加大液压或加大垂直压力均不会
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A.
caught
B.
made
C.
took
D.
got
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A.
from the general to the particular
B.
from the particular to the general
C.
from the whole topic to its parts
D.
from question to answer or from effect to cause
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