Perfective yes-no questions are yes-no questions used to ask about the completion of an action, like, for example, “Have you seen this movie (yet)?” in English.
In Vietnamese, we use đã and chưa to form perfective yes-no questions.
General structure
Structure
Place đã before a verb or an adjective, and chưa at the end of the sentence to form a perfective yes-no question.
đã + verb / adj. + … + chưa?
Examples
Exception
There is a verb that can follow a modified version of the general structure above: là (“to be”).
Structure
Place đã phải before là, and chưa at the end of the sentence.
đã phải + là + obj. + … + chưa?
In some cases, là can be omitted without affecting the meaning.
đã phải + obj. + … + chưa?
Examples
Extended structure
You can add hay or hay là (“or“) before chưa. The meaning stays the same, but this extended structure is more common in embedded questions.
Structure
đã + verb / adj. + … + hay + chưa?
đã + verb / adj. + … + hay là + chưa?
Examples
Usage notes
For short sentences, it’s common to omit đã.
This structure of perfective yes-no questions doesn’t work well with some adverbs: đều (“all”), cũng (“also”), sẽ (“will”), etc. You should use presumptive yes-no questions or tag questions instead.