趁 (chèn) is a preposition that means to 'take advantage of' an opportunity or favorable time to do something. It is normally followed by an adjective or a short phrase explaining the situation that the person is seeking to take advantage of.

Basic Structure

趁+[situation/opportunity]
Examples

Chèn láobǎn bú zài, wǒmen chūqu chī fàn bɑ.
趁 老板 不 在，我们 出去 吃 饭 吧。
When the boss wasn't here, we went out to eat.

Chèn niánqīnɡ, nǐmen kuài diánér jiéhūn bɑ.
趁 年轻，你们 快 点儿 结婚 吧。
You guys should hurry up and get married while you're still young.

Chèn háizi shuìzháo de shíhou, wǒ xǐ le hěn duō yīfu.
趁 孩子 睡着 的 时候，我 洗 了 很 多 衣服。
While the kids were asleep, I washed a lot of clothes.

Chèn tiānqì hǎo, wǒ yào shài bèi.
趁 天气 好，我 要 晒 被。
While the weather is good, I'm going to go out and enjoy the sun.