你必須事先預約。

You have to make a reservation.

Source: Tatoeba

Sentence Composition

=1 你 nǐ you (informal, as opposed to courteous 您 nín)
=1 你 nǐ you (Note: In Taiwan, 妳 is used to address females, but in mainland China, it is not commonly used. Instead, 你 is used to address both males and females.)
2 必須 bìxū
  1. to have to
  2. must
  3. compulsory
  4. necessarily
3 事先 shìxiān
  1. in advance
  2. before the event
  3. beforehand
  4. prior
4 預約 yùyuē
  1. booking
  2. reservation
  3. to book
  4. to make an appointment