biga waseo ppallaereul bang ane neoreo dueosseoyo.

Here 와서 is from 오다 (to come) and the grammar -아서/어서.

In weather expressions, 비가 오다 means to rain. So:

• 비가 와서 = because it rained / because it’s raining
• more literally: rain comes, so...

In this sentence, -아서/어서 connects the reason to the next action:

• 비가 와서 빨래를 방 안에 널어 두었어요.
• Because it was raining, I hung the laundry inside and left it there.

So 와서 is not just and came here; it gives the idea of because/since.

Because 비 is the subject of the verb 오다 in the expression 비가 오다 (it rains).

• 비가 오다 = rain falls / it rains
• 가 marks 비 as the subject

You should learn 비가 오다 as a set expression.

Why not the others?

• 비는 would mark 비 as the topic, which is possible in some contexts, but 비가 오다 is the most basic neutral form.
• 비를 오다 is incorrect.

So in ordinary Korean, 비가 와서 is the natural choice.

In a connected sentence, the first verb often appears in a plain connective form rather than a fully polite ending.

So:

• 비가 와서 = because it rained / because it’s raining
• the politeness is shown at the end of the whole sentence: 두었어요

That is very normal in Korean. Usually only the final verb carries the speech level.

As for tense, Korean often does not mark tense in the reason clause if it is clear from context. So 와서 can naturally connect to a past action.

This is a very common Korean pattern.

Even when the whole situation is in the past, the earlier connected clause often stays in the simple -아서/어서 form:

• 비가 와서 ... 두었어요
• literally something like It rained / was raining, so ... I hung it and left it.

Korean does not always mark past tense on every verb the way English often does. The final verb 두었어요 already places the sentence in the past, so 와서 sounds natural.

If you over-mark everything for tense, it can sound heavy or unnatural.

빨래 usually means laundry or the clothes being washed / washed clothes.

Depending on context, it can refer to:

• the act of doing laundry
• the laundry itself
• clothes that need drying

In this sentence, 빨래를 널다 means to hang up the laundry (to dry).

So here 빨래 is best understood as the laundry / washed clothes.

Because 빨래 is the object of 널다 (to hang/spread out).

• 빨래를 널다 = to hang the laundry
• 를 is the object marker

So the structure is:

• 비가 와서 = because it was raining
• 빨래를 = the laundry (object)
• 방 안에 = inside the room
• 널어 두었어요 = hung it up and left it that way

방 안에 means inside the room.

Breakdown:

• 방 = room
• 안 = inside
• 에 = location/destination marker

So 방 안에 is literally in the inside of the room.

This is a very common Korean pattern:

• 집 안에 = inside the house
• 가방 안에 = inside the bag
• 상자 안에 = inside the box

Because this sentence focuses on where the laundry was placed/hung, not mainly on where the action happened.

• 에 is often used for the place where something ends up or exists
• 에서 is often used for the place where an action happens

Since 널다 here leads to the laundry being located there, 방 안에 sounds natural.

Compare:

• 빨래를 방 안에 널었어요.
  = I hung the laundry in the room / inside the room.

• 방 안에서 빨래를 널었어요.
  = I hung the laundry while in the room.
  This focuses a bit more on the location of the action itself.

In many situations both can be understandable, but 에 is very natural here.

널다 means to hang out, to spread out, especially for drying.

A very common expression is:

• 빨래를 널다 = to hang up the laundry

It is specifically useful for clothes, blankets, and similar things that are spread or hung so they can dry.

Examples:

• 빨래를 밖에 널었어요. = I hung the laundry outside.
• 수건을 널어 두세요. = Hang the towels up and leave them there.

This is one of the most important points in the sentence.

널어 두었어요 = hung it up and left it that way

It comes from:

• 널다 = to hang
• -어 두다 = do something and leave it in that state / do something in advance for later

So:

• 널었어요 = I hung it.
• 널어 두었어요 = I hung it and left it hanging / I put it there and kept it that way.

The 두다 adds the idea of a resulting state or preparation. It often feels like:

• did it and left it like that
• did it in advance
• did it for a purpose

That nuance is very natural here, because laundry is normally hung and then left hanging to dry.

Because the speaker is not only describing the action of hanging the laundry, but also the fact that it was left indoors afterward.

Compare:

• 빨래를 방 안에 널었어요.
  = I hung the laundry inside.

• 빨래를 방 안에 널어 두었어요.
  = I hung the laundry inside and left it there.

The second version gives a stronger sense that the laundry is still in that state, or that the action was done as a practical response to the rain.

Yes.

두었어요 is past tense because the action of putting/hanging it there happened in the past. But because of -어 두다, it often implies that the result of that past action still matters now.

So it can mean something like:

• I hung it up earlier and left it that way.

This is very common in Korean: a past form can describe a completed action whose result still remains relevant.

Yes, very often.

• 널어 두었어요
• 널어 놓았어요

Both can mean hung it up and left it that way.

The difference is subtle:

• -어 두다 often emphasizes doing something and keeping it that way, sometimes with a sense of preparation or management.
• -어 놓다 often emphasizes the resulting state after placing/setting something.

In everyday speech, they overlap a lot, and many learners will hear both.

It is polite informal style, often called -어요/-아요 style.

So this sentence is polite and natural in everyday conversation:

• with strangers
• with coworkers
• with older people in many casual situations
• in normal spoken Korean

It is not the formal -습니다 style.

Formal version:

• 비가 와서 빨래를 방 안에 널어 두었습니다.

Yes.

In this sentence, English may translate it as either:

• Because it was raining, I hung the laundry inside
• Because it was raining, I left the laundry hanging in the room

The exact time reference depends on context. Since the final verb is past tense, many learners naturally understand the rain as part of the past situation too.

So 비가 와서 here does not force a strictly present-time meaning.

The structure is:

• 비가 와서 = because it rained / because it was raining
• 빨래를 = the laundry
• 방 안에 = inside the room
• 널어 두었어요 = hung it up and left it there

So the general Korean order is:

reason + object + place + verb

This matches a common Korean pattern where most information comes before the final verb.

Yes, somewhat.

Korean word order is more flexible than English, as long as the particles make the roles clear. For example, these can still be understandable:

• 비가 와서 방 안에 빨래를 널어 두었어요.
• 빨래를 비가 와서 방 안에 널어 두었어요.
  This is less neutral, but still possible in context.

The most natural and neutral order is usually the original one:

• 비가 와서 빨래를 방 안에 널어 두었어요.

So learners should treat the original sentence as a very good default model.