bottom operation 是什么意思？

bottom operation 是什么意思？

bottom operation
底层操作
例句：
1.
The leaks will then be plugged during the bottom kill, an operation officials say is not expected to be completed until late august.
一名操作人员称，底部封堵过程中，泄漏将被封住，但这将持续到8月底。
2.
Mouse operation, the bottom of the game have different buttons control different tasks.
鼠标操作，游戏下方有不同的按钮控制不同的工作。
3.
Staring up from the bottom of the deepest pipe in the world's most ambitious plumbing operation, the view is that of a frog in a well: a small distant disc of light grey sky.
在世界最宏伟的管道施工现场，从最深的管底向上望去，直觉得自己是“井底之蛙”：浅灰色的天空有如不远处的小碟子。
4.
This was a great event for paul, who sat down on the bottom stair, and watched the operation attentively: now and then glancing at the clock face, leaning all askew, against the wall hard by, and feeling a little confused by a suspicion that it was ogling him.
对保罗来说，这是一件大事；他在楼梯最低的一级上坐下来，专心致志地看着正在进行的操作；有时向歪斜地靠在近旁墙上的钟面看一眼，心中有些不安地猜疑，它正在向他送秋波吧。
5.
Improper operation of bottom hole pump workers fall yesterday 0:33, king bridge near the city of kunming, wang hunan prison next to the construction company on site, in a race against time to rescue the well started.
液压泵操作不当工人跌落井底昨日零时33分，王大桥附近昆明监狱旁湖南望城建筑公司工地上，一场与时间赛跑的深井救援开始了。

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