vt.

1. 使变暗；使变黑；使加深
   Thick clouds darkened the sky before the rain fell.

   下雨前厚厚的云层遮暗了天空。

2. 使模糊；使难懂
3. 使（眼睛）失明
4. 使阴郁，使不快
   The argument darkened her mood.

   那场争吵弄得她心情很不愉快。

vi.

1. 变暗；变黑；变深
2. 变得模糊；变得难懂
3. 变得阴郁
   His face darkened with anger.

   他气得沉下脸来。

v.

1. make or become dark or darker.
2. make or become unhappy or angry.
   ▸(of someone's eyes or expression) show anger.