何时

In a sentence

• 你何时会到达北京？

  When will you arrive in Beijing?

  Here, '何时' is used to inquire about a specific point in time, demonstrating its role as a question word for 'when'.

• 老师问学生们何时完成了作业。

  The teacher asked the students when they completed their homework.

  In this case, '何时' serves to ask about the timing of a past event, maintaining its function as an inquiry for 'when'.

• 我不清楚他何时离开办公室。

  I am not sure when he left the office.

  Here, '何时' is used in reported speech or indirect question to reference an uncertain time, retaining its meaning of 'when'.