The preposition 趁
We use the preposition 趁 
when we speak about actions that should be done before circumstances change.
For example: “we have to go while we’re still invited” or “let's go while we can”.
when we speak about actions that should be done before circumstances change.
For example: “we have to go while we’re still invited” or “let's go while we can”.
Scheme
趁
some circumstances
action
The preposition 趁 is usually stated either at the beginning of a sentence or at the beginning of the second clause in a compound sentence.
Examples
趁火车还没开，你现在还能下车
You can still get off now while the train is not moving
chèn huǒchē hái méi kāi, nǐ xiànzài hái néng xiàchē
她趁别人还没醒，溜出了房子
She slipped out before the others woke up
tā chèn biérén hái méi xǐng, liū chū le fángzi
我们很早就起床出发了，趁天还没热
We got up early and headed out before it got hot
wǒmen hěn zǎo jiù qǐchuáng chūfā le, chèn tiān hái méi rè