4 sentences for 开机 (kāi​jī — power on)

1. 他手机还是没开机。

   tā shǒu​jī hái​shi méi kāi​jī.

   His phone is still turned off.

   Source: OpenSubtitles

2. 电脑开机后需要几分钟加载程序。

   diàn​nǎo kāi​jī hòu xū​yào jǐ fēn​zhōng jiā​zài chéng​xù.

   The computer takes a few minutes to load programs after starting up.

   Source: Dong Chinese Dictionary

3. 橱窗里摆放的手机其实是假货，并不能开机使用。

   chú​chuāng lǐ bǎi​fàng de shǒu​jī qí​shí shì jiǎ​huò, bìng bù néng kāi​jī shǐ​yòng.

   The phones in the display window are actually mockups and cannot be turned on for use.

   Source: Dong Chinese Dictionary

4. 当电脑系统失去响应时，用户可以通过按下开机热键来尝试重启。

   dāng diàn​nǎo xì​tǒng shī​qù xiǎng​yìng shí, yòng​hù kě​yǐ tōng​guò àn​xià kāi​jī rè​jiàn lái cháng​shì chóng​qǐ.

   When the computer system stops responding, users can try to restart it by pressing the power hotkey.

   Source: Dong Chinese Dictionary