时
shí
Expressing "when" with "shi"
时 is the compact written form of 的时候.
Verb / Time + 时
How it works
考试时不要说话 — no talking during the exam. Signs, notices and formal writing prefer 时 for its brevity.
In speech people say 的时候. Using 时 in casual conversation sounds bookish.
Examples
kǎo shì shí bú yào shuō huà
考试时不要说话。
No talking during the exam.
shàng kè shí qǐng guān shǒu jī
上课时请关手机。
Please switch off your phone during class.
kāi chē shí bú yào kàn shǒu jī
开车时不要看手机。
Don't look at your phone while driving.