有一种叫做沟槽支撑的东西——一种用于挡住沟壁的金属箱体——挖土超过五英尺约1.5米时，用它来防止塌方。
There's something called a trench box - a metal case that holds back the sides of the walls - to be used to stop them caving in when you dig deeper than 5ft.
有一种叫做沟槽支撑的东西——一种用于挡住沟壁的金属箱体——挖土超过五英尺约1.5米时，用它来防止塌方。
There's something called a trench box - a metal case that holds back the sides of the walls - to be used to stop them caving in when you dig deeper than 5ft.
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