Definition

1. Interrogative phrase:
   • How long? (duration): Used to ask about the length of time an action or state lasts.
   • How much longer? / In how long? (future point): Used to ask about the amount of time remaining until a future event happens.

Usage Examples

• Asking about duration:
  • Anh sẽ ở đây bao lâu? (How long will you stay here?)
  • Chuyến bay kéo dài bao lâu? (How long does the flight last?)
• Asking about a future point:
  • Bao lâu nữa thì xe buýt đến? (How much longer until the bus arrives? / In how long will the bus arrive?)
  • Chúng ta phải đợi bao lâu? (How long do we have to wait?)

Advanced Usage

• 'không bao lâu': not long, soon, before long. This phrase indicates that something will happen after a short period of time.
  • Cô ấy vừa mới đến, và không bao lâu sau thì anh ấy cũng tới. (She had just arrived, and not long after, he came too.)
  • Họ sẽ trở về không bao lâu nữa. (They will return before long.)

Variants and Related Words

• Bao nhiêu lâu?: This is a very close synonym and is often used interchangeably with 'bao lâu' to ask "how long?" in terms of duration.
  • Anh đã học tiếng Việt bao nhiêu lâu? (How long have you been studying Vietnamese?)
• Lâu: (Adjective/Adverb) A long time. This is the core word meaning "long" in terms of time.
  • Đã lâu rồi tôi không gặp cô ấy. (It's been a long time since I saw her.)

Synonyms

• Trong bao lâu?: For how long? (Emphasizes the span of time within which something occurs).
• Mất bao lâu?: How long does it take? (Specifically asks about the time required to complete an action).

Related Phrases

• Được bao lâu?: How long has it been? / How long will it last? (Often used to question the sustainability or current duration of a state).
  • Mối quan hệ này sẽ được bao lâu? (How long will this relationship last?)
• Bao lâu một lần?: How often? (Literally: "How long once?" – used to ask about frequency).
  • Bạn tập thể dục bao lâu một lần? (How often do you exercise?)