肯定有人看見發生了什麼。

Someone must've seen what happened.

Somebody must've seen what happened.

Someone must have seen what happened.

Somebody must have seen what happened.

Source: Tatoeba

Sentence Composition

1 肯定 kěndìng
  1. to be certain; to be positive
  2. assuredly; definitely
  3. to give recognition; to affirm
  4. affirmative (answer)
2 有人 yǒurén
  1. someone
  2. people
  3. anyone
  4. there is someone there
  5. occupied (as in restroom)
3 看見 kànjiàn to see; to catch sight of
4 發生 fāshēng to happen; to occur; to take place; to break out
=5 了 le
  1. (completed action marker)
  2. (modal particle indicating change of state, situation now)
  3. (modal particle intensifying preceding clause)
=5 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)
=5 了 liǎo
  1. (of eyes) bright
  2. clear-sighted
  3. to understand clearly
=5 了 liào unofficial variant of 瞭 liào
6 什麼 shénme
  1. what?
  2. something; anything