Modem ở trong nhà.

• modem = modem
• ở = to be located; to be at/in
• trong = inside, in
• nhà = house, home

So the sentence is literally something like Modem is located inside house/home.

Vietnamese does not always use a separate verb like English to be.

In this sentence, ở is doing the main job. It means to be at / to be in / to be located at. So:

• Modem ở trong nhà = The modem is in the house.

You do not need a separate word meaning is here.

Here, ở is best understood as a location verb meaning to be at / to stay at / to be located in.

So the structure is:

• subject + ở + place

Examples:

• Tôi ở Hà Nội. = I live/am in Hanoi.
• Điện thoại ở trên bàn. = The phone is on the table.

For English speakers, it may feel a bit like a mix of is and at/in.

Yes, but they do different jobs:

• ở = marks that something is located somewhere
• trong = specifies the spatial relationship inside

So:

• Modem ở nhà = The modem is at home / at the house.
• Modem ở trong nhà = The modem is inside the house.

Using both is very natural because ở introduces the location, and trong nhà tells you what kind of location it is.

It can mean either house or home, depending on context.

• nhà often means the physical house/building.
• It can also mean home in a more personal sense.

So trong nhà can be understood as:

• in the house
• inside the home

In this sentence, in the house is probably the most literal translation.

Vietnamese does not use articles the way English does.

English needs:

• a modem
• the modem
• a house
• the house

Vietnamese often leaves that information to context:

• modem can mean a modem or the modem
• nhà can mean a house, the house, or home

So Modem ở trong nhà could mean:

• The modem is in the house.
• A modem is in the house.

Usually context tells you which one is meant.

Not necessarily.

For many everyday nouns, especially objects, Vietnamese often uses a classifier such as cái. But classifiers are not required in every sentence.

So both can occur:

• Modem ở trong nhà.
• Cái modem ở trong nhà.

The version with cái may sound a little more specific or concrete, especially if you are talking about a particular physical object. Without cái, the sentence is still perfectly normal.

Yes, fairly similar.

The pattern is:

• Modem = subject
• ở = location verb
• trong nhà = place phrase

So it works like:

• The modem + is + in the house

That makes this a fairly beginner-friendly sentence.

Yes. Modem is a borrowed technical word.

In writing, Vietnamese commonly just uses modem. In speech, people usually pronounce it in a Vietnamese way, roughly syllable by syllable, rather than exactly like English pronunciation.

So for a learner, the important point is:

• it is a normal borrowed noun
• it behaves like other Vietnamese nouns in the sentence

It can give that general idea, but literally it means The modem is inside the house/home.

If the context is simply whether the modem is inside or outside, then indoors may be a natural English translation. But word-for-word, trong nhà is specifically inside the house/home.

A very common way is:

• Modem có ở trong nhà không? = Is the modem in the house?

Another casual spoken option is:

• Modem ở trong nhà à? = The modem is in the house?

The first one is the safer, standard pattern for learners.

You can say:

• Modem không ở trong nhà.

Pattern:

• không goes before ở

So:

• Modem ở trong nhà. = The modem is in the house.
• Modem không ở trong nhà. = The modem is not in the house.