一定要告訴他們喔。

Make sure you tell them.

Source: Tatoeba

Sentence Composition

1 一定要 yīdìngyào must
=2 告訴 gàosù to press charges; to file a complaint
=2 告訴 gàosu to tell; to inform; to let know
3 他們 tāmen they; them
=4 喔 ō (interjection) oh; I see (used to indicate realization, understanding)
=4 喔 o (Tw) (sentence-final particle) (used to convey a friendly tone when giving an admonition or correcting sb etc)
=4 喔 wō
  1. (onom.) cry of a rooster (usu. reduplicated)
  2. Taiwan pr. wò
=4 喔 wò
  1. Particle conveying realization or surprise.
  2. the sound of a chicken: cluck