2 sentences for 开关 (kāi​guān — open and close)

1. 频繁开关电脑会缩短其使用寿命。

   pín​fán kāi​guān diàn​nǎo huì suō​duǎn qí shǐ​yòng shòu​mìng.

   Frequently turning a computer on and off can shorten its lifespan.

   Source: Dong Chinese Dictionary

2. 这扇门太久没上油，开关时感觉很涩。

   zhè shàn mén tài jiǔ méi shàng​yóu, kāi​guān shí gǎn​jué hěn sè.

   The door hasn't been oiled for a long time, so it feels stiff when opening or closing it.

   Source: Dong Chinese Dictionary