电梯的关门按钮真的是毫无用处的吗？
Is it true that the elevator close-door button is completely useless?
关门系统在同时按下两个关门“CLOSE”按钮时才能正常关闭。
The door closed only on the two "CLOSE" switches is touched at the same time.
关门系统在同时按下两个关门“CLOSE”按钮时才能正常关闭。
The door closed only on the two "CLOSE" switches is touched at the same time.
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