biga waseo undonghwaga jeojeosseoyo.

Here, 와서 means because it rained or so/and then it rained, depending on how naturally you translate it.

It comes from:

• 오다 = to come
• 비가 오다 = to rain
• -아서/어서 = a connector meaning because, so, or sometimes just linking two events

So:

• 비가 와서 = because it rained

In this sentence, it shows a cause-and-result relationship:

• 비가 와서 = because it rained
• 운동화가 젖었어요 = the sneakers got wet

So the whole sentence is basically: Because it rained, the sneakers got wet.

Because Korean often contracts vowels when conjugating.

The verb is 오다.
When you attach -아서, you first get:

• 오 + 아서

But 오아 contracts to 와, so:

• 오아서 → 와서

This is a very common contraction:

• 오다 → 와요
• 보다 → 봐요
• 오다 + 아서 → 와서

So 비가 와서 is the natural correct form.

Because each part of the sentence has its own subject.

1. 비가 와서

   • 비가 = the rain / it
   • subject of 오다 (to rain)

2. 운동화가 젖었어요

   • 운동화가 = the sneakers
   • subject of 젖다 (to get wet)

So Korean is not using 가 twice on the same subject. It is marking the subject of each clause separately.

A natural way to think about it is:

• Rain came, so the sneakers got wet.

Each event has its own subject.

Using 가 here sounds like a neutral description of what happened.

• 비가 와서 = it rained / because it rained
• 운동화가 젖었어요 = the sneakers got wet

가 often marks the subject as the thing directly involved in the event.

If you used 는, it could sound more like setting up a topic or making a contrast. For example:

• 비는 와서... might feel like as for the rain...
• 운동화는 젖었어요 could sound like the sneakers, at least, got wet or contrast them with something else

So in a simple factual sentence like this, 가 is very natural.

운동화 means sneakers, athletic shoes, or tennis shoes.

Breakdown:

• 운동 = exercise, sports
• 화 = shoe (in Sino-Korean vocabulary)

So 운동화 literally means something like exercise shoes.

It is more specific than 신발, which just means shoes in general.

For example:

• 신발이 젖었어요 = My shoes got wet.
• 운동화가 젖었어요 = My sneakers got wet.

젖었어요 is the past polite form of 젖다, which means to get wet or to become wet.

Conjugation:

• dictionary form: 젖다
• past stem: 젖었-
• polite ending: 어요

So:

• 젖었어요 = got wet / became wet / were wet

In Korean, the past tense often describes the result of a change too. So this can sound like:

• The sneakers got wet
• The sneakers are wet now because they got wet

Both ideas fit well depending on context.

Mostly, it means the sneakers got wet.

But Korean past tense can also imply the resulting state, so in context it can feel like:

• The sneakers got wet
• The sneakers are wet now

That is because 젖다 describes a change into a wet state.
So 젖었어요 often suggests both:

1. the change happened
2. the result still matters now

That is very natural in Korean.

Because Korean often leaves out possessives like my, your, or his/her when they are obvious from context.

So:

• 운동화가 젖었어요 can naturally mean my sneakers got wet

If you really want to specify, you can say:

• 제 운동화가 젖었어요 = my sneakers got wet (polite)
• 내 운동화가 젖었어요 = my sneakers got wet (casual)

But if the speaker is obviously talking about their own shoes, Korean usually does not need the possessive.

They are similar, but not exactly the same.

비가 와서

• literally: because it rained
• uses a full verb clause
• feels very natural for describing a cause-and-result event

비 때문에

• literally: because of rain
• uses a noun (비)
• focuses more on the cause as a thing

So these are both possible:

• 비가 와서 운동화가 젖었어요.
• 비 때문에 운동화가 젖었어요.

The first one emphasizes it rained, while the second emphasizes the rain as the reason.

Also, if you want to use 때문에 with a verb, you need -기 때문에:

• 비가 오기 때문에 = because it rains / because it is raining

Not always. -아서/어서 can do a few related jobs.

It can mean:

1. because

   • 비가 와서 운동화가 젖었어요.
   • Because it rained, the sneakers got wet.

2. simple sequence or connection

   • 집에 가서 쉬었어요.
   • I went home and rested.

So the exact meaning depends on context.

In your sentence, the relationship is clearly cause and result, so because is the best way to understand it.

A natural pronunciation is roughly:

• 비가 와서 운동화가 저저써요

More carefully:

• 비가 = bi-ga
• 와서 = wa-seo
• 운동화가 = un-dong-hwa-ga
• 젖었어요 sounds roughly like 저저써요

The main thing learners often notice is:

• 와서 is one smooth word, not 오아서
• 젖었어요 is pronounced more smoothly than it looks in spelling

So the whole sentence flows naturally as:

• 비가 와서 운동화가 저저써요