这个东西的玻璃盖是用活动接头从中间接起来的。
遇 到需连接管道的长度比设计长度短的情况时，活动接头还可以起到延长管道的作用，使用 效果好。
When the length of a pipeline needing to be connected is shorter than the designed length, the movable connector can play a role in prolonging the pipeline and has good use effect.
伸缩缝处立柱接头有芯柱连接上下柱，通常设计为可活动的接头。
Expansion joints in the column joints have core column connection column from top to bottom, usually designed to be movable joints.
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