Learn Hardcore Vietnamese: Tôi đã xem phim và nghe âm nhạc cùng bạn bè hôm qua. - I watched a movie and listened to music with friends yesterday.

đã is the marker for past tense in Vietnamese. It indicates that the actions “xem phim” and “nghe âm nhạc” happened already (yesterday). Without đã, the sentence could sound like a general present habit.

Why don’t we use a preposition like “to” between the verbs and their objects (e.g., “to watch the movie”)?

Vietnamese verbs take their objects directly without a separate preposition. So xem phim literally means “watch movie,” where xem is “watch” and phim is “movie.”

What’s the difference between cùng bạn bè and với bạn bè for “with friends”?

Both cùng and với can mean “with,” but:

cùng bạn bè often emphasizes doing something together as a group.
với bạn bè is more neutral, simply stating accompaniment.
In casual speech, they’re largely interchangeable here.

Why is it nghe âm nhạc instead of nghe nhạc, and do we need any classifier before âm nhạc?

nghe nhạc is the everyday phrase (“listen to music”).
nghe âm nhạc sounds slightly more formal or literary (“listen to music”).
No classifier is required because âm nhạc/nhạc is an uncountable noun. You only add classifiers if you specify quantity (e.g., một bản nhạc).

Could we use vừa… vừa… to indicate that the two actions happened at the same time?

Yes. If you want to stress that you were doing both simultaneously, you could say:
Tôi vừa xem phim vừa nghe nhạc với bạn bè hôm qua.
Here vừa… vừa… = “both…and…”; it highlights concurrent actions more than simple và.

Why is hôm qua placed at the end of the sentence rather than at the beginning?

Time expressions like hôm qua are flexible. Putting it at the end is very common in conversational Vietnamese. If you start with it, you’d say: Hôm qua, tôi đã xem phim…, which is also correct but sounds slightly more formal or written.

What’s the difference between xem and nhìn when talking about movies?

xem means “to watch” (TV, film, show).
nhìn means “to look (at), to glance.”
You always use xem phim (“watch a movie”), never nhìn phim.

Is it necessary to repeat và before nghe âm nhạc? Could we omit it?

When listing two actions performed by the same subject, you need và (or vừa… vừa…) to connect them:
Tôi đã xem phim và nghe âm nhạc…
Without và, the sentence would be ungrammatical or ambiguous.