他心不在焉。

He's absent-minded.

Source: Tatoeba

Sentence Composition

1 他心 tāxīn
  1. (literary) ulterior motives
  2. ulterior motives
2 不在 bùzài
  1. not to be present
  2. to be out
  3. (euphemism) to pass away
  4. to be deceased
3 焉 yān
  1. where
  2. how