Cửa sổ trong phòng đang mở.

The window in the room is open.

Breakdown of Cửa sổ trong phòng đang mở.

• đang: currently
• trong: in
• phòng: the room
• cửa sổ: the window
• mở: to open

Questions & Answers about Cửa sổ trong phòng đang mở.

Why is there no copula like là (the equivalent of “to be”) in Cửa sổ trong phòng đang mở?

In Vietnamese, when you describe a state or quality, you usually place the adjective or stative verb directly after the noun without a linking verb.
• Cửa sổ mở literally “window open” = “the window is open.”
You only use là when you equate or identify two nouns:
• Đó là cửa sổ = “That is a window.”

What does đang express in Cửa sổ trong phòng đang mở? Is it mandatory?

đang marks the progressive or ongoing aspect, emphasizing that the action/state is happening right now.
• đang mở = “is opening” or “is (currently) open.”
If you simply want to state a general or permanent fact, you can omit đang:
• Cửa sổ trong phòng mở.

What’s the difference in meaning between Cửa sổ trong phòng mở and Cửa sổ trong phòng đang mở?

• Cửa sổ trong phòng mở – a simple present/predicate: “The window in the room is open” (timeless or general state).
• Cửa sổ trong phòng đang mở – emphasizes “right now” the window is open or is in the process of opening.

Why is the phrase trong phòng used instead of ở trong phòng, and why does it come after cửa sổ?

• trong phòng (“inside the room”) is a prepositional phrase placed directly after the noun it modifies. In Vietnamese modifiers (prepositional phrases, relative clauses, adjectives) follow the head noun.
• ở trong phòng would be used when you want to state someone’s or something’s location with the verb ở (“to be at/in”):
– Tôi ở trong phòng = “I am in the room.”
But to say “the window in the room,” you drop ở and just use trong phòng as a noun modifier.

Can mở act as both a verb and an adjective? How can I tell which it is here?

Yes.
• As a verb (action): Tôi mở cửa sổ = “I open the window.”
• As an adjective/stative verb (state): Cửa sổ mở = “The window is open.”
In Cửa sổ trong phòng đang mở, it’s stative, describing the window’s condition, but with đang it leans toward an ongoing event (“is in the process of opening”).

How would I negate this sentence? For example, how do I say “The window in the room is not open”?

You have two main options:
1) Use the antonym đóng (“closed”):
• Cửa sổ trong phòng đóng.
2) Use không before mở for a literal “not open”:
• Cửa sổ trong phòng không mở.

Could I front-load trong phòng and say Trong phòng, cửa sổ đang mở? Would that sound natural?

Yes, you can topicalize trong phòng for emphasis by putting it at the very beginning:
• Trong phòng, cửa sổ đang mở.
This structure highlights the location (“As for the room, the window is open”), but the basic meaning stays the same.

If I want to ask “Is the window in the room open?”, how do I form a question?

In spoken Vietnamese you can simply raise your intonation, or add a question word/particle:
• Cửa sổ trong phòng đang mở không? (yes/no question)
• Cửa sổ trong phòng đã mở chưa? (using đã… chưa to ask “Has the window been opened yet?”)