趁 + Condition, Action
The preposition 趁 (chèn) means "while" or "taking advantage of" a favorable condition or moment. It introduces a time window or opportunity that the speaker urges someone to act on before it passes. For instance, you might say 趁年轻多学点东西, meaning "while you're young, learn more things."
趁现在有空,赶紧把作业写完吧。
Chèn xiànzài yǒu kòng, gǎnjǐn bǎ zuòyè xiě wán ba.
Take advantage of the free time now and hurry up and finish your homework.
趁天还没黑,我们早点出发。
Chèn tiān hái méi hēi, wǒmen zǎo diǎn chūfā.
Let's set out early while it's not dark yet.
趁老板心情好,你去跟他提加薪的事。
Chèn lǎobǎn xīnqíng hǎo, nǐ qù gēn tā tí jiāxīn de shì.
While the boss is in a good mood, go talk to him about a raise.