趁【chèn】

趁 introduces a condition that suits the action and won't last, and the rest of the sentence says what you do while it does. It can take an adjective, a noun or a whole clause.

With a clause, 趁 often catches a moment when someone isn't looking.

趁着 is the same, slightly fuller. 趁机 is "take the chance", and 趁早 is "while there's still time, sooner rather than later".

趁 or 在…的时候

在…的时候 just says when. 趁 says the moment is an advantage you're using.

A situation that works against the action can't follow 趁.

• × 趁下雨，我们没去公园 → 因为下雨，我们没去公园