Please make sure all mobile phones are switched off during the performance.

请确保演出时关上所有手机。

《牛津词典》

In one scan, both phones were switched off.

第一次扫描时，两只手机都关掉。

youdao

Once it has reached its cruising altitude, its "fasten seatbelt" sign will be switched off-and so will a new "no phones" light alongside it.

一旦飞机到达其巡航高度，“请系上安全带”的提示灯就会熄灭，在其旁边新增的“请不要打电话”提示灯同时也会熄灭。

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Bandwidth - which in the UK will come when the analogue signal is switched off - needs to be freed up by regulators and manufacturers have to provide phones that can cope with TV viewing alongside the myriad other functions already eating up battery life.

BBC: Man in India on mobile phone

Despite being a leader in in-flight Wi-Fi, the United States bans the use of mobiles on flights, requiring that phones are switched off once they enter U.S. airspace.

CNN: In-flight phone calls to become standard, say experts