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。
1. Mum will light up when she realises we've planned a surprise party for her.
2. 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。
A: Hurry! We're going to miss the train!
B: Lighten up – there'll be another one five minutes later.
Tower Bridge in London has had a new lighting system installed which enhances the bridge's architectural features. Static lights have been replaced with bulbs that can vary in intensity and colour. The world-famous bridge gleamed white to celebrate the Queen's Diamond Jubilee and the more energy-efficient lights were switched on after that.