他当时一个人在家。

He was home alone at the time.

Source: Tatoeba

Sentence Composition

1 他 tā
  1. (third-person singular) (since the early 20th century, usu. male) he; him; his
  2. (bound form) other; another; some other (as in 他日 tārì and 他人 tārén)
=2 当时 dāngshí
  1. then
  2. at that time
  3. while
=2 当时 dàngshí
  1. at once
  2. right away
3 一个人 yīgèrén
  1. by oneself (without assistance)
  2. alone (without company)
4 在家 zàijiā
  1. to be at home
  2. (at a workplace) to be in (as opposed to being away on official business 出差 chūchāi)
  3. (Buddhism etc) to remain a layman (as opposed to becoming a monk or a nun 出家 chūjiā)