gyeoureneun gaseubiga bissaseo ttatteushan oseul deo ibeo.

겨울에는 means in winter or as for winter.

It is made of:

• 겨울 = winter
• 에 = a particle often used for time expressions like at / in / on
• 는 = topic marker

So 겨울에는 gives a sense of:

• in winter
• when it comes to winter
• as for winter, ...

The 는 also adds a slight contrastive feeling. It can imply something like:

• In winter, gas bills are expensive...
  (possibly different from other seasons)

So this is not just a plain time phrase; it also helps set winter up as the topic or contrast.

가스비 means gas bill or gas expense.

It is a very common Korean word pattern:

• 가스 = gas
• 비 = expense, cost, fee

So:

• 전기비 = electricity bill/cost
• 교통비 = transportation cost
• 식비 = food expenses
• 관리비 = maintenance fee

In everyday Korean, 비 is often attached to a noun to mean the cost for that thing.

가스비가 uses the subject marker 가 because gas bills are the thing being described as expensive.

In this sentence:

• 가스비가 비싸서 = because gas bills are expensive

Here, 가스비 is the subject of 비싸다 (to be expensive), so 가/이 is natural.

A learner might wonder why it is not 가스비는. It could be 가스비는 in some contexts, but that would shift the nuance more toward as for gas bills... or contrast them with something else. In this sentence, 가스비가 is the straightforward choice.

비싸서 is the -아서/어서 connective form of 비싸다.

• 비싸다 = to be expensive
• 비싸서 = because it is expensive / and so it is expensive

In this sentence, it connects the reason to the result:

• 가스비가 비싸서 따뜻한 옷을 더 입어.
• Because gas bills are expensive, I wear more warm clothes.

The ending -아서/어서 is very commonly used to mean:

• because
• so
• and therefore

Here it expresses the reason for the action in the second part.

Yes, you often could say 비싸니까, but the nuance is a little different.

• 비싸서 = because it’s expensive / so it’s expensive
• 비싸니까 = since it’s expensive / because it’s expensive

Both can give a reason, but:

• -아서/어서 often sounds like a natural cause-and-result connection.
• -(으)니까 often feels a bit more explicit, logical, or speaker-judgment-based.

So:

• 가스비가 비싸서 따뜻한 옷을 더 입어.
  = Gas bills are expensive, so I wear warmer clothes / more warm clothes.

• 가스비가 비싸니까 따뜻한 옷을 더 입어.
  = Since gas bills are expensive, wear more warm clothes / I wear more warm clothes.
  Depending on context, -니까 can sometimes sound more like reasoning or advice.

In this sentence, 비싸서 sounds very natural for a simple explanation of behavior.

Because Korean adjectives change form when they directly describe a noun.

The dictionary form is:

• 따뜻하다 = to be warm

When it modifies a noun, 하다 adjectives usually become -한:

• 따뜻한 옷 = warm clothes

This is like saying:

• 예쁘다 → 예쁜
• 작다 → 작은
• 조용하다 → 조용한

So:

• 따뜻한 옷 = warm clothes
• 따뜻한 방 = a warm room
• 따뜻한 차 = warm tea

This is the normal noun-modifying form.

더 means more.

So:

• 따뜻한 옷을 더 입어 = wear more warm clothes / wear warmer or extra warm clothes

Depending on context, 더 can mean:

• more
• additionally
• to a greater degree

Examples:

• 더 먹어. = Eat more.
• 더 커요. = It’s bigger.
• 옷을 더 입어. = Put on more clothes.

In this sentence, it suggests wearing extra layers or more clothing than usual.

Because 입다 means to wear / put on, and the thing being worn is its direct object.

So:

• 옷을 입다 = to wear clothes
• 코트를 입다 = to wear a coat
• 신발을 신다 = to wear shoes
• 모자를 쓰다 = to wear a hat

Here:

• 옷 = clothes
• 을 = object marker
• 입어 = wear / put on

So 옷을 is marked as the thing the action is being done to.

입어 is the informal, non-polite present form of 입다.

From 입다:

• 입어 = wear / put on
  informal casual speech
• 입어요 = polite everyday speech
• 입는다 = plain style, often used in writing or self-talk

So this sentence is in casual speech, probably something you’d say to:

• a friend
• someone younger
• yourself
• in notes/examples

If you want a polite version, you could say:

• 겨울에는 가스비가 비싸서 따뜻한 옷을 더 입어요.

Yes. The subject is omitted, which is very common in Korean.

The sentence does not explicitly say:

• I wear
• we wear
• you should wear

It just says:

• In winter, because gas bills are expensive, wear more warm clothes.

Who the subject is depends on context. In many situations, it would naturally mean:

• I wear more warm clothes or
• We wear more warm clothes

If said to someone directly, it might even sound like casual advice:

• Wear more warm clothes because gas bills are expensive in winter.

Korean often leaves out subjects when they are understood from context.

It can suggest either, depending on context.

입다 covers both:

• to put on
• to wear

In English, we often separate these ideas more clearly, but Korean does not always.

In this sentence, 따뜻한 옷을 더 입어 most naturally means:

• I wear more warm clothes
• I put on extra warm clothes
• I layer up more

So the idea is not just one moment of putting clothes on, but generally wearing extra clothing in winter to avoid using too much gas heating.

Yes. Starting with 겨울에는 frames the whole sentence around the season and gives it a contrastive background.

It can feel like:

• In winter, ...
• When it’s winter, ...
• As for winter, ...

The 는 suggests that winter is being highlighted, possibly in contrast with other times:

• 겨울에는 가스비가 비싸서...
  = In winter, gas bills are expensive, so...

This is a very common Korean way to organize a sentence: start with the time or setting, then explain what happens in that context.

Yes, it is natural. The overall nuance is:

• In winter, gas bills are expensive, so I wear more warm clothes.

It sounds like a practical everyday statement about saving heating costs by wearing extra clothes.

A few natural English-style interpretations are:

• In winter, gas bills are expensive, so I wear warmer clothes.
• In winter, gas is expensive, so I put on more warm clothes.
• Since the gas bill is high in winter, I wear extra warm clothes.

The sentence feels conversational and realistic, especially in casual spoken Korean.