Clause/Phrase + 时
时 (shí) means "when" or "at the time of." It is placed after a clause or phrase to indicate the moment when something happens, functioning similarly to "when" in English. For example, 听到语言时 means "when hearing the language."
听到这个消息时,他正在开会。
Tīngdào zhège xiāoxi shí, tā zhèngzài kāihuì.
When he heard the news, he was in a meeting.
下雨时,记得把窗户关上。
Xià yǔ shí, jìde bǎ chuānghù guānshàng.
When it rains, remember to close the windows.
小时候,我经常跟爷爷去河边钓鱼。
Xiǎoshíhou, wǒ jīngcháng gēn yéye qù hébiān diàoyú.
When I was little, I often went fishing by the river with my grandfather.