i saendeuwichieneun chijeuga deureogayo.

이 means this. It directly modifies the noun 샌드위치 (sandwich), so 이 샌드위치 means this sandwich.

It works like:

• 이 = this
• 그 = that
• 저 = that over there

So:

• 이 샌드위치 = this sandwich
• 그 샌드위치 = that sandwich
• 저 샌드위치 = that sandwich over there

Because 에는 is made of particles, and Korean particles attach directly to the noun they follow.

Here:

• 샌드위치 = sandwich
• 에 = in/on/at
• 는 = topic marker

So 샌드위치에는 is not one dictionary word. It is:

• 샌드위치 + 에 + 는

This is very normal in Korean. Particles are written attached to the noun:

• 학교에 = at school
• 물은 = as for water
• 샌드위치에는 = as for/in this sandwich

에는 is 에 + 는.

• 에 marks the place or location: in the sandwich
• 는 adds topic or contrast

So 이 샌드위치에는 has a nuance like:

• as for in this sandwich
• in this sandwich, at least
• this sandwich contains...

The 는 often gives a slight contrastive feeling, especially when talking about ingredients, menus, or options. For example, it can suggest something like:

• This sandwich has cheese in it
  possibly implying that another sandwich may not.

If you said 이 샌드위치에 치즈가 들어가요, that is also natural, but it sounds a bit more neutral and less contrastive.

Because 치즈 is not being treated as a direct object here. It is the thing that goes in / is included.

The verb 들어가다 literally means to go in, enter. With this verb, the item being included is commonly marked with 가/이, not 를/을.

So:

• 치즈가 들어가요 = cheese goes in / cheese is included not
• 치즈를 들어가요 = incorrect

Think of it this way:

• with 넣다 (to put in), you often use 를
  • 치즈를 넣어요 = put in cheese
• with 들어가다 (to go in / be included), you often use 가
  • 치즈가 들어가요 = cheese goes in / is included

들어가요 comes from 들어가다.

Literally, 들어가다 means:

• to go in
• to enter

But in food-related contexts, it often means:

• to be included
• to contain
• to have ... in it

So 치즈가 들어가요 literally is something like:

• cheese goes in

But naturally in English, it means:

• it contains cheese
• cheese is included

This is a very common Korean way to talk about ingredients:

• 이 음식에는 마늘이 들어가요. = This dish contains garlic.
• 설탕이 들어가요. = Sugar goes in / Sugar is included.

Korean and English organize information differently.

This sentence is:

• 이 샌드위치에는 = in/as for this sandwich
• 치즈가 = cheese
• 들어가요 = goes in / is included

So the literal order is roughly:

• In this sandwich, cheese goes in.

Korean usually puts the verb at the end. That is one of the biggest word-order differences from English.

A very rough breakdown is:

• topic/location first
• subject next
• verb last

So even though the natural English translation is This sandwich contains cheese, the Korean structure is closer to In this sandwich, cheese is included.

In Korean, the present tense is often used for general facts, descriptions, recipes, and ingredient information.

So 치즈가 들어가요 does not mean the cheese is physically moving into the sandwich right now. It means:

• cheese is included
• cheese belongs in it
• this sandwich has cheese in it

This is similar to how English sometimes uses the present tense for general truths:

• This soup has onions in it.
• This recipe uses butter.

In Korean food contexts, the present tense is very common for this kind of statement.

Yes, you can. That sentence is natural too.

The difference is mainly nuance:

• 이 샌드위치에 치즈가 들어가요
  = In this sandwich, cheese is included.
  More neutral.

• 이 샌드위치에는 치즈가 들어가요
  = As for this sandwich, cheese is included.
  Adds topic/contrast emphasis.

So if you are comparing menu items, ingredients, or choices, 에는 is especially common and useful.

Yes. 들어가요 is in the standard polite style, often called 해요체. It is appropriate in everyday conversation, shops, restaurants, and most normal situations.

Levels:

• 들어가요 = polite
• 들어가 = casual
• 들어갑니다 = more formal

So the sentence can change like this:

• 이 샌드위치에는 치즈가 들어가요.
  polite, everyday

• 이 샌드위치에는 치즈가 들어가.
  casual, to friends or younger people

• 이 샌드위치에는 치즈가 들어갑니다.
  formal, customer service, announcements, written explanations

Sometimes, yes, but the nuance is a little different.

• 들어가요 focuses on what is included / what goes into it
• 들어 있어요 focuses more on what is in there / what is inside

So:

• 이 샌드위치에는 치즈가 들어가요.
  = This sandwich contains cheese.
  This is very natural when talking about ingredients or menu information.

• 이 샌드위치에는 치즈가 들어 있어요.
  = There is cheese inside this sandwich.
  This can also be natural, but it emphasizes the state of being inside.

In restaurant or recipe contexts, 들어가요 is extremely common for ingredients.

They are loanwords.

• 샌드위치 = sandwich
• 치즈 = cheese

Korean has many loanwords, especially for foods, technology, and modern culture. These are written in 한글 to match Korean pronunciation.

A rough pronunciation guide:

• 샌드위치 ≈ saen-deu-wi-chi
• 치즈 ≈ chi-jeu

Even though they come from English, their Korean pronunciation and spelling follow Korean sound patterns, so they will not sound exactly like the English words.