Dầu ăn ở trong chảo.

Dầu ăn means cooking oil or edible oil.

• dầu = oil
• ăn = eat

When combined, dầu ăn literally means oil for eating/for cooking, not just any kind of oil. So it refers to food-safe oil, not things like motor oil or essential oil.

In dầu ăn, ăn is part of a fixed noun phrase, not the main action of the sentence.

So:

• dầu = oil
• dầu ăn = cooking oil / edible oil

This is very common in Vietnamese: a verb can help describe the purpose of a noun. Here, ăn tells you this is the kind of oil used for food.

Ở trong means in or inside.

It is made of:

• ở = to be at, to be located at
• trong = inside

Together, ở trong gives the idea is located inside.

So Dầu ăn ở trong chảo means the cooking oil is located inside the pan.

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

In location sentences, ở often does the job of is at / is in.

So:

• Dầu ăn ở trong chảo = The cooking oil is in the pan.

Do not use là here.
Là is used for identity or definition, not location.

• Correct: Dầu ăn ở trong chảo.
• Incorrect: Dầu ăn là trong chảo.

Sometimes yes, but it depends on the structure.

Ở trong chảo is a complete location predicate:

• Dầu ăn ở trong chảo.

If you remove ở, then trong chảo is just a prepositional phrase meaning in the pan. It usually needs something else in the sentence:

• Có dầu ăn trong chảo. = There is cooking oil in the pan.
• Dầu ăn đang trong chảo. = The cooking oil is in the pan.
  (less common than using ở)

So for a simple basic sentence meaning is in the pan, ở trong is very clear and natural.

The structure is:

Subject + location verb + place

So:

• Dầu ăn = subject
• ở trong = location phrase/verb phrase
• chảo = place noun

Full breakdown:

• Dầu ăn = cooking oil
• ở trong chảo = is in the pan

This is a very common Vietnamese pattern for saying where something is.

Vietnamese often leaves out classifiers like cái unless they are needed.

• chảo = pan
• cái chảo = the pan / a pan, with classifier

In many simple location statements, the bare noun is perfectly normal:

• Dầu ăn ở trong chảo.

If you want to be a bit more specific or conversational, you could also say:

• Dầu ăn ở trong cái chảo.

Both are understandable. The version without cái is shorter and very normal.

Usually chảo means a frying pan, skillet, or sometimes a wok-like pan, depending on context.

It is generally a pan used for frying or cooking on the stove. It does not usually mean a pot.

For comparison:

• chảo = pan
• nồi = pot

So in this sentence, chảo is the container the oil is in.

Usually no, because trên means on or on top of, while trong means in or inside.

Oil is normally thought of as being in the pan, so:

• trong chảo = in the pan

Using trên chảo would sound like the oil is somehow on the surface of the pan in a more external sense, which is not the normal way to describe it.

So trong chảo is the natural choice.

Yes, it is grammatical and understandable.

It is a straightforward location sentence: The cooking oil is in the pan.

Depending on context, native speakers might also say things like:

• Có dầu ăn trong chảo. = There is cooking oil in the pan.
• Dầu ăn đang ở trong chảo. = The cooking oil is in the pan right now.

But Dầu ăn ở trong chảo is still a good, correct sentence for learning this structure.