Learn Hardcore Vietnamese: Tôi đã mua vé rạp chiếu phim hôm qua.

đã is the perfective (or past) aspect marker. It goes between the subject and the verb to show that the action is completed. Vietnamese verbs don’t conjugate for tense like English. Instead you add particles (like đã for past, sẽ for future) to indicate time.

Can I drop đã and just say Tôi mua vé rạp chiếu phim hôm qua?

Yes, dropping đã is common in casual speech when you already specify the time with hôm qua. The listener will still understand it as past.
– With đã: emphasizes “I already bought.”
– Without đã: more neutral, still clearly past because of hôm qua.

Why is hôm qua (“yesterday”) at the end? Can it go elsewhere?

Time expressions in Vietnamese are quite flexible. You can place hôm qua at the beginning or the end:
– Hôm qua tôi đã mua vé rạp chiếu phim.
– Tôi đã mua vé rạp chiếu phim hôm qua.
Both are correct. Putting it first can add emphasis or set the time frame before the main clause.

What exactly does rạp chiếu phim mean? Can I shorten it?

rạp = “hall,” chiếu phim = “to show a movie.” Together it means “movie theater” or “cinema.”
Common shorter forms:

rạp phim (colloquial)
rạp (if context is clear)

Why say vé rạp chiếu phim instead of simply vé phim or vé xem phim?

vé rạp chiếu phim literally means “ticket for the cinema.”
vé xem phim (“ticket to watch a film”) is equally natural.
vé phim by itself is uncommon because vé (“ticket”) usually needs either the action (xem) or the place (rạp chiếu phim) to specify what it’s for.

How do I indicate how many tickets I bought? Do I need a classifier?

If you want to specify quantity, add a number and the same word vé acts like its own classifier:

Tôi đã mua một vé rạp chiếu phim. (I bought one cinema ticket.)
Tôi đã mua hai vé rạp chiếu phim. (I bought two cinema tickets.)
If you don’t mention a number, it’s understood you bought at least one but the exact count is not important.

How would I ask, “Did you buy movie tickets yesterday?” in Vietnamese?

You can use either the chưa question or the có… không structure:
1) Với chưa (perfective question):
Hôm qua bạn đã mua vé rạp chiếu phim chưa?
2) Với có… không (yes/no question with topic-marker có):
Hôm qua bạn có mua vé rạp chiếu phim không?

What’s the difference between using đã and rồi to show a completed action?

Both mark completion, but their placement and nuance differ:

đã goes before the verb: Tôi đã mua vé…
rồi goes after the verb (or verb phrase): Tôi mua vé rồi.
đã is more neutral/simple past. rồi often implies “already” or “by now,” and can feel more colloquial. You can combine them for extra emphasis: Tôi đã mua vé rồi.