Learn Hardcore Vietnamese: Bạn đã xem phim đó chưa?

đã is an aspect marker indicating that the action is completed or in the past. Vietnamese verbs don’t change form for tense; instead you add đã (past), đang (ongoing), sẽ (future), etc.
Example:

Bạn đã xem phim đó chưa? (“Have you watched that movie yet?”)

What role does chưa play at the end of the sentence?

chưa in questions asks if something has not happened yet. Placed at the end, it turns a statement into a yes–no question about completion.

Bạn đã xem phim đó = “You have watched that movie.”
Bạn đã xem phim đó chưa? = “Have you watched that movie yet?”

Why is the order đã xem and not xem đã?

In Vietnamese, aspect markers like đã always come before the verb they modify. Putting đã after the verb would be ungrammatical.

Can I omit đã and just say Bạn xem phim đó chưa?

Yes. Dropping đã is common in informal speech.

Bạn xem phim đó chưa? still means “Have you seen that movie?”
The past sense is implied by chưa? at the end.

What’s the difference between đã and rồi?

Both convey completed action, but their positions differ:

đã goes before the verb: Bạn đã xem…
rồi usually goes after the verb or at the end: Bạn xem phim đó rồi chưa?
You can even use them together: Bạn đã xem phim đó rồi chưa? for emphasis.

How do I answer Bạn đã xem phim đó chưa??

Short answers:

Rồi. (“Yes, I have.”)
Chưa. (“No, I haven’t.”)
Longer replies:
Rồi, mình đã xem rồi.
Chưa, mình chưa xem.

Can I replace bạn with other pronouns?

Yes. Choose pronouns by age/gender/context:

Anh đã xem… chưa? (to an older male)
Chị đã xem… chưa? (to an older female)
Em đã xem… chưa? (to someone younger)
Cậu/Ông/Bà… or a name also works: Hải đã xem phim đó chưa?

When should I use đó, này, or kia after phim?

These are demonstratives referring to distance or context:

phim này = “this movie” (near speaker)
phim đó = “that movie” (near listener or previously mentioned)
phim kia = “that movie over there” (far from both)

How do I ask “Did you watch that movie last night?”

Just add the time phrase, typically before đã (or at the end):

Bạn tối qua đã xem phim đó chưa?
Bạn đã xem phim đó tối qua chưa?