誰在敲門？

Who's knocking on the door?

Source: Tatoeba

Sentence Composition

1 誰 shéi
  1. who
  2. also pr. shuí
2 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)
3 敲門 qiāomén to knock on a door