There is an LED that gets activated when the tap is turned on and deactivated when turned off, this results in a stream of coloured waterfall in your sink or basin.

水龙头里的发光二极管能够随着水龙头的拧开和关紧而开启或关闭，这样流到水槽或面盆里的水就会像彩色的小瀑布一般。

youdao

What did you do? 10.39.29 April We were in the room when they turned off the machine.

BBC

But when she turned off the ignition and turned it on again, and tried the starter with the choke out, the engine fired at once.

NEWYORKER: The Woman of the House

Control of the pipelines meant that when Gazprom turned off the gas (as it did in 2009 in a dispute over trans-shipments through Ukraine), buyers had nowhere to turn for alternatives.

ECONOMIST: Shale gas should make the world a cleaner, safer place