bite one's lip字面意思：咬嘴唇；实际意思： 欲言又止，克制住，忍住要说的话。

【例句】
It was scary. A dozen times I wanted to yell 'Not so fast! Not so fast!' or 'Look out for that car!' But I managed to bite my lip and we got through it without an accident.
那真吓人。有好多次我都想大叫:“别开那么快! 别开那么快!”或者“当心那辆车!”但是我竭力忍住了没开口。我们总算平安无事地开完了这趟车。

I just had to bite my lip while the boss yelled at me for losing the account.
由于失去客户，老板朝我大呼大闹，而我只能克制住我自己。