Learn Hardcore Filipino: Nasa loob ng kwarto si Maria ngayon.

sa is a general preposition: sa kwarto = in/at the room.
nasa is usually used in predicates to say where something is:
Nasa kwarto si Maria. = Maria is in the room.

You can think of it this way:

sa = to/at/in (used in phrases)
nasa = is at / is in (used to say the location of a subject)

In many cases, nasa + place works like the English predicate is in + place at the start of a Filipino sentence.

Why do we say nasa loob ng kwarto instead of just nasa kwarto?

Both are correct, but they differ slightly in nuance:

Nasa kwarto si Maria. – Maria is in the room.
Nasa loob ng kwarto si Maria. – Maria is inside the room.

loob literally means inside / inner part / interior.

loob ng kwarto = inside of the room or the interior of the room.

Using loob puts extra emphasis on the idea of being inside, not just generally at the room area. It’s similar to the difference between:

at the room vs.
inside the room

What is the role of ng in loob ng kwarto?

ng is a linker/marker that often shows possession or a part–whole relationship, similar to of in English.

In loob ng kwarto:

loob = inside / interior
kwarto = room
ng links them: loob ng kwarto ≈ interior of the room / inside of the room

Structure:
[loob] + ng + [container/place]

Other examples:

loob ng bag – inside the bag
loob ng bahay – inside the house

Why is there a si before Maria?

si is a special marker that shows the following word is a personal name and is functioning as the subject/topic of the sentence.

si Maria – (the person) Maria
si Juan – Juan
si Dr. Santos – Dr. Santos

Some points:

si is not the same as English the. It’s more like a grammatical tag for named people.
You do not use si with common nouns:
❌ si babae (wrong)
✅ ang babae (the woman)

In Nasa loob ng kwarto si Maria ngayon, si Maria is the person whose location we’re talking about.

Why does the sentence start with nasa loob ng kwarto instead of starting with si Maria?

Filipino commonly uses predicate–first word order:

[Predicate] + [Subject/Topic]

In this sentence:

Predicate (what is being said about the subject):
Nasa loob ng kwarto – is inside the room
Subject/Topic (who we’re talking about):
si Maria

So we get:
Nasa loob ng kwarto si Maria.

You can also say:

Si Maria ay nasa loob ng kwarto ngayon.

That version uses ay and looks more like English Maria is inside the room now, and it sounds more formal or written.

Both orders are correct; the predicate‑first pattern is more natural in everyday spoken Filipino.

What does ngayon do here, and where can it go in the sentence?

ngayon means now / today / at present. It tells us when Maria is inside the room.

In your sentence:

Nasa loob ng kwarto si Maria ngayon.
= Maria is inside the room now.

Other natural positions:

Ngayon, nasa loob ng kwarto si Maria. – Now, Maria is inside the room.
Nasa loob ng kwarto ngayon si Maria. – still natural; the focus is slightly more on now.

Filipino is fairly flexible with adverb placement, but ngayon often appears at the end or at the very beginning of the sentence.

How would you say Maria is not inside the room now?

The most natural way is to use wala (absence / non‑existence) plus sa + place:

Wala si Maria sa loob ng kwarto ngayon.
Literally: Maria is absent from inside the room now.

You can also say:

Wala sa loob ng kwarto si Maria ngayon.

Using hindi directly with nasa (for example: Hindi nasa loob ng kwarto si Maria) is grammatically possible but sounds awkward or unnatural to many speakers. For locations, wala … sa … is preferred.

Can any words be dropped in casual speech, like si or ngayon?

ngayon (now):
This can be dropped if the time is already clear from context:
Nasa loob ng kwarto si Maria. – Maria is inside the room.
(It can still be understood as now if you are talking about the present.)
si (personal name marker):
This cannot normally be dropped in correct Filipino.
❌ Nasa loob ng kwarto Maria. (unnatural/wrong)
✅ Nasa loob ng kwarto si Maria.

So, you can safely omit ngayon when the timing is understood, but keep si before personal names in standard Filipino.

What does kwarto mean, and is it the same as kuwarto or silid?

kwarto means room, usually understood as bedroom in many contexts.

kwarto and kuwarto are variants of the same word (from Spanish cuarto).
Some people spell it kwarto (modernized), others kuwarto (more traditional). Pronunciation is basically the same.
silid also means room, but it can feel a bit more formal or bookish, especially in compounds:
- silid‑aralan – classroom
- silid‑tulugan – bedroom

In everyday speech about a bedroom, kwarto / kuwarto is very common.

How do you pronounce nasa loob ng kwarto si Maria ngayon?

Approximate pronunciation (Tagalog standard):

nasa – NA‑sa (stress on na) – /ˈnasa/
loob – lo‑OB (2 syllables: lo‑ob; often with a slight glottal stop between o and o): /loˈʔob/ or /loˈob/
ng – a velar nasal sound, like final ng in sing: /ŋ/
kwarto – KWAR‑to (stress on kwar): /ˈkwarto/
si – see: /si/
Maria – ma‑REE‑ya: /maˈɾija/ (r is a flap, like the Spanish r in pero)
ngayon – roughly nga‑YON: /ŋaˈjon/

Full sentence:
/ˈnasa loˈʔob naŋ ˈkwarto si maˈɾija ŋaˈjon/

Spoken naturally, some syllables will be reduced a bit, but this gives you a close guide.

What is the difference between ng (as in this sentence) and nang?

In your sentence, you only see ng, not nang, but they often confuse learners.

ng (pronounced /ŋ/):

Used as:
- linker/marker for objects: Kumain siya ng mangga. – He/She ate mango.
- linker between nouns: loob ng kwarto – inside of the room
Comes before nouns or adjectives, never before a verb in this function.

nang (pronounced the same, /ŋaŋ/ or /naŋ/ depending on accent):

Has several uses, including:
- before verbs/adjectives as a linker, or to mean when, so that, in order to, etc.
  Umalis siya nang maaga. – He/She left early.

In loob ng kwarto, ng is correct because it is linking loob and kwarto.

Is this sentence talking about a temporary situation (right now) or a general fact?

The presence of ngayon makes it clearly about the current time:

Nasa loob ng kwarto si Maria ngayon.
= Maria is inside the room right now.

Without ngayon, it could still describe a present situation, but less explicitly time‑bound:

Nasa loob ng kwarto si Maria.
= Maria is in the room. (understood as now, if you are talking about the current moment)

Filipino does not use a verb to be for this kind of location sentence, so time/aspect is often clarified with adverbs like ngayon (now), kanina (earlier), mamaya (later), etc.