当某人 lights up, 这意味着他/她看起来很高兴或为什么事情而感到欣喜。

例句

Mum will light up when she realises we've planned a surprise party for her.

My grandma would light up when she talked about the olden days.

请注意

另一个字面相似的短语 lighten up 意思和 light up 不一样，这是劝某人应该放松一些，不要太紧张或太在意某件事情。

Hurry! We're going to miss the train!

Lighten up – there'll be another one five minutes later.