vi.
发亮，发光；生色：
The room brightened after she had changed the curtains.
她换了窗帘后那个房间变得明亮了。
快活，活泼，活跃；开颜：
The girls brightened(up) when they reached the park.
姑娘们一到公园就高兴起来了。
vt.
使发亮，使发光；使生色：
Brighten the kitchen by painting it yellow.
给厨房涂上黄色，使它发亮。
使活泼，使光耀；使高兴，