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。
