Definition

1. Interrogative Adverb:

   • When: Used to ask about a specific point in time or a future occasion.
   • Ever (in negative contexts): Used in rhetorical questions or negative statements to mean "never" or "at no time."

2. Relative Adverb:

   • When(ever): Used to introduce a subordinate clause referring to an unspecified or conditional time.

Usage Examples

• Interrogative Adverb:

  • Khi nào bạn sẽ trở lại? (When will you return?)
  • Khi nào tôi lại nỡ làm thế? (When would I ever be so heartless as to do that? / I would never be so heartless as to do that.)

• Relative Adverb:

  • Hãy gọi cho tôi khi nào bạn sẵn sàng. (Call me when(ever) you are ready.)
  • Khi nào làm xong báo cho tôi biết. (When you have finished, please let me know.)

Advanced Usage

• Used in fixed negative constructions to express "never" or strong refusal.
  • Khi nào tôi đồng ý với ý kiến đó! (I would never agree with that opinion!)

Variants and Related Words

• Bao giờ: An interchangeable synonym for "khi nào" in both interrogative and relative uses, meaning "when" or "ever."
• Lúc nào: Another synonym, often used more casually to mean "when."

Synonyms

• When: At what time.
• Whenever: At any or every time that.
• Never (in negative rhetorical use): At no time; not ever.

Related Idioms and Phrases

• Khi nào có dịp: Whenever there's an opportunity/chance.
  • Chúng ta nên gặp lại khi nào có dịp. (We should meet again whenever we get the chance.)
• Biết khi nào...: Used to express uncertainty about the timing of a future event.
  • Biết khi nào cô ấy mới đến. (Who knows when she will arrive.)

1. When
   • Khi nào làm xong báo cho tôi biết
     When you have finished the job, please let me know
2. Never
   • Khi nào làm lại một việc chướng như thế
     One should never do such an unsemly thing