The reasonable approach is to do the basic flow once, do a loop once, and then do a loop a second time.

最合理的方法是做一遍基本流程，一遍循环流程，然后再做一遍循环流程。

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Figure 1 shows the basic steps in the loop and how they are related.

图1显示了循环中的各个基本步骤以及它们之间的关系。

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Firstly, the logic control system is the most basic loop of all elevator systems.

首先，逻辑控制环节是电梯控制的最基本环节。

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Firstly, the logic control system is the most basic loop of all elevator systems.

首先，逻辑控制环节是电梯控制的最基本环节。

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