他們獨自在圖書館裡。

They were alone in the library.

Source: Tatoeba

Sentence Composition

1 他們 tāmen they; them
2 獨自 dúzì alone
3 在 zài
  1. to exist; to be alive
  2. (of sb or sth) to be (located) at
  3. (used before a verb to indicate an action in progress)
4 圖書館 túshūguǎn library

classifiers: 家, 個
5 裡 lǐ
  1. lining
  2. interior
  3. inside
  4. internal
  5. also written 裏 lǐ