冬天太冷，他的嘴唇都冻紫了。

Dōngtiān tài lěng, tā de zuǐchún dōu dòngzǐ le.

It was so cold in winter that his lips turned purple from the cold.

医生让我张开嘴巴，他要检查我的嘴唇和牙齿。

Yīshēng ràng wǒ zhāngkāi zuǐba, tā yào jiǎnchá wǒde zuǐchún hé yáchǐ.

The doctor asked me to open my mouth; he wanted to examine my lips and teeth.

他的嘴唇微微颤抖，看上去很紧张。

Tā de zuǐchún wēiwēi chàndǒu, kàn shàngqu hěn jǐnzhāng.

His lips were trembling slightly, and he looked very nervous.