key应该指向想要打开的信号量集的key值。
Key should point to the semaphore set key, which you want to open.
youdao
关闭危险信号灯，打开左转灯。
Turn off your hazard lights and turn on your left turn signal.
打开放大器电源，选择节目信号源。
Turn on the amplifier and select the program source.
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