问题
多项选择题
组成机械密封的主要部件是（）。
A、由动环、静环组成的密封副
B、以弹性元件为主的补偿缓冲件
C、辅助密封圈
D、使动环与轴一起旋转的传动件
答案
参考答案：A, B, C
搜题请搜索小程序“爱下问搜题”
组成机械密封的主要部件是（）。
A、由动环、静环组成的密封副
B、以弹性元件为主的补偿缓冲件
C、辅助密封圈
D、使动环与轴一起旋转的传动件
参考答案：A, B, C
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| Every day some people are killed while they are crossing the roads. 1___________ of these people are old people and children. Old people are often killed because they can't see or 2___________ very well. Children are killed because they are not 3___________. They forget to look and listen before they 4___________ the roads. A car or a bus can't stop 5__________. If a car is going very fast, it will travel many metres 6__________ it stops. Some people don't always understand this. They think a car can stop 7___________ a few metres. It is difficult to 8___________ how fast a car is moving. The only way to cross the roads safely is to look 9___________ ways, right and left. Then if the roads are 10___________, you can cross them.
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