Crack a smile指的是微笑或露齿一笑：

　　例句：

　　They were a tough class to teach, I told my best jokes and no one even cracked a smile.

　　他们真是很难教的一个班级。我讲了我最棒的笑话，居然没有一个人笑。

　　Crack a smile还可以用来表示在感觉不想微笑的时候挤出一丝笑容：

　　例句：

　　She told me a joke at the party and it just wasn't funny, I tried to crack a smile but just couldn't.

　　她在聚会上给我讲了一个笑话，但一点也不好笑，我试着挤出一丝笑容，但做不到。

　　Force a smile指的是在你不想微笑的情况下微笑：

　　例句：

　　Even though I didn't want to be there, I managed to force a smile for the cameras.

　　虽然我并不想在那儿，我还是为了镜头强迫自己露出笑容。

　　Smile from ear to ear 指的是很快乐很满足的大笑，有眉开眼笑的意思：

　　例句：

　　After hearing the results of his exam he walked around campus with a smile from ear to ear.

　　听到他的考试成绩后，他眉开眼笑地在校园里漫步。

　　Wipe the smile off/from someone's face 指的是让某人笑不出来，尤其是那些自以为很聪明而惹人厌的人：

　　例句：

　　I know the other team cheated, they were off side all day, I would love to wipe the smile from their faces but will have to wait until the next time we play them.

　　我知道另一队作弊了，他们一整天都在越位犯规，我很想让他们笑不出来，但得等到下次我们跟他们较量时了。