Grin/Smile from ear to ear:
To look extremely happy.
“Grin from ear to ear” 或者 “smile from ear to ear” 用来描述某人 “开心地咧嘴大笑，笑得合不拢嘴”。
例句
When I got my exam results, I was grinning from ear to ear.
当我拿到考试成绩时，我开心极了，笑得合不拢嘴。
I grinned from ear to ear when I heard about my promotion.
听到升职的消息，我笑开了花。
It was his birthday, so no wonder he was grinning from ear to ear!
那天是他的生日，怪不得他当时咧着嘴笑得那么开心。
