合不拢嘴

tā xiào de hé bu lǒng zuǐ

他笑得合不拢嘴。

He was grinning all over his chops.

tā hū rán miàn lù xiào yì lè de hé bu lǒng zuǐ

她忽然面露笑意，乐得合不拢嘴。

Her face broke into a wide smile.