The traditional escalator works by turning the steps upside down and looping them underneath the staircase to take them back to the start.

传统手扶电梯的工作原理是依靠楼梯上升后，在终点处回环，再变做楼梯下面继续运行，从而实现楼梯的颠倒，重复循环使用；

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The traditional escalator works by looping its stairs underneath the staircase to take them back to the start. Half the steps are therefore hidden away and never in use.

传统电梯上下需各使用一条传送带，且每条传送带都要转到扶梯下面，因此有一半是隐藏在下面不用的。

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