天空突然變暗了。

All of a sudden the sky became dark.

Source: Tatoeba

Sentence Composition

1 天空 tiānkōng sky
2 突然 tūrán sudden; abrupt; unexpected
3 變暗 biànàn to darken
=4 了 le
  1. (completed action marker)
  2. (modal particle indicating change of state, situation now)
  3. (modal particle intensifying preceding clause)
=4 了 liǎo
  1. to finish
  2. (used with 得 dé or 不 bù after a verb to express (im)possibility, as in 忘不了 wàngbuliǎo "cannot forget")
  3. (literary) (usually followed by a negative such as 无 wú or 不 bù) completely (not); entirely (not); (not) in the least
  4. to understand clearly (variant of 了 liǎo)
=4 了 liǎo
  1. (of eyes) bright
  2. clear-sighted
  3. to understand clearly
=4 了 liào unofficial variant of 瞭 liào