brighten up

1．become bright or brighter 放晴

The sky brightened up after the storm passed．暴风雨过后，天空放晴了。

2．make more cheerful or lively 使…愉快；使…增辉

His face brightened up．他脸上露出了喜色。

They brightened the party up with music and dancing．他们的歌舞活跃了晚会的气氛。