Bạn còn ở trong văn phòng à?

In this sentence, còn means still.

So Bạn còn ở trong văn phòng à? means something like:

• Are you still in the office?
• You’re still in the office?

It suggests that the speaker expected the person might have left already.

They do different jobs:

• ở = to be/stay at, in
• trong = inside/in

So ở trong văn phòng literally means be inside the office.

A very natural shorter version is:

• Bạn còn ở văn phòng à?

Adding trong puts a bit more focus on being physically inside the office.

À is a sentence-final particle used to make the sentence sound like a question, often with a tone of:

• surprise
• checking
• realization
• mild curiosity

So this sentence can feel like:

• Oh, you’re still in the office?
• Are you still in the office?

It is not exactly the same as plain English are; it adds attitude or feeling.

Vietnamese has more than one way to ask yes/no questions.

Here, the speaker uses à instead of không.

Compare:

• Bạn còn ở trong văn phòng à?
  = You’re still in the office? / Are you still in the office?
  Often sounds like the speaker is reacting to something or is a bit surprised.

• Bạn còn ở trong văn phòng không?
  = Are you still in the office?
  More neutral and straightforward.

So à is often a little more conversational and expressive.

No. Bạn is common, but it depends on who you are talking to.

Bạn works well when speaking to:

• a friend
• someone around your age
• a classmate or colleague in a casual setting

But Vietnamese often uses kinship-style pronouns instead, such as:

• anh for an older male
• chị for an older female
• em for a younger person
• cô / chú / bác for older adults, depending on age and relationship

So depending on the situation, the sentence might become:

• Anh còn ở trong văn phòng à?
• Chị còn ở trong văn phòng à?

Yes, absolutely.

• Bạn còn ở văn phòng à? = very natural
• Bạn còn ở trong văn phòng à? = also natural, but a bit more specific about being physically inside

In many everyday situations, Vietnamese speakers would probably just say ở văn phòng unless they want to stress inside the office.

Yes, you could.

Both còn and vẫn can relate to the idea of still, but they are not identical.

• còn often suggests remaining or still being there
• vẫn often emphasizes continuing unchanged

Examples:

• Bạn còn ở trong văn phòng à?
  = Are you still in the office?

• Bạn vẫn ở trong văn phòng à?
  = Are you still in the office?
  Slightly more focused on the situation continuing.

• Bạn vẫn còn ở trong văn phòng à?
  = also very natural, and often even more emphatic: Are you still in the office?

In casual speech, vẫn còn is very common.

Vietnamese does not always use a separate verb like English am / is / are.

Here, ở functions as the main verb and means to be/stay at/in a place.

So:

• Bạn = you
• còn = still
• ở = be/stay
• trong văn phòng = in the office
• à = question particle

That is why there is no separate word equivalent to English are.

Yes, normally it asks about the person’s current location.

It means the speaker thinks:

• maybe you should have left already
• maybe it is late
• maybe they are surprised you are still there

It does not usually mean Do you still work in the office?

If you want to talk about someone’s work arrangement, you would usually need a different sentence.

Often, yes.

The combination of còn and final à often gives a feeling like:

• You’re still there?
• Oh, you’re still in the office?

The exact tone depends on context and intonation, but many learners should understand that this is not just a cold, neutral question. It often carries some reaction from the speaker.

Sometimes, yes, if the context is already clear.

For example, in a text conversation, someone might simply say:

• Còn ở trong văn phòng à?

This would still mean:

• Are you still in the office?

Vietnamese often drops subjects when they are obvious from context. But for learners, keeping bạn is usually safer and clearer.

A few very natural versions are:

• Bạn còn ở văn phòng à?
• Bạn vẫn còn ở văn phòng à?
• Còn ở văn phòng à?
• Vẫn còn ở văn phòng à?

All of these can mean Are you still in the office?, with small differences in emphasis and formality.