kosmuri gyesok nawaseo maseukeureul gyesok sseugo isseosseo.

콧물이 is 콧물 + 이.

• 코 = nose
• 물 = water
• 콧물 = nasal mucus, snot, a runny nose
• 이 = subject particle

So 콧물이 means the nasal mucus / my runny nose as the subject of the clause.

In Korean, people often describe a runny nose with the expression 콧물이 나다, which literally means snot comes out.

The particle 이/가 marks the subject.

Here, the thing that is coming out is 콧물, so it takes the subject particle:

• 콧물이 나와서 = because mucus was coming out / because my nose was running

Since 콧물 ends in a consonant, the subject particle is 이, not 가.

나와서 comes from 나오다, which means to come out.

Breakdown:

• 나오다 = to come out
• 나와서 = comes out and..., or because it comes out...

In this sentence, -아서/어서 is being used with a reason/cause meaning:

• 콧물이 계속 나와서 = because my nose kept running

So even though 나오다 literally means come out, in this context it is the natural Korean way to talk about mucus or nasal discharge.

Both uses of 계속 mean continuously / continually / keep...ing, but they modify different parts of the sentence.

• 콧물이 계속 나와서 = because my nose kept running
• 마스크를 계속 쓰고 있었어 = I kept wearing a mask

So the sentence emphasizes two ongoing things:

1. the runny nose did not stop
2. the mask-wearing also continued

You could remove one 계속 if the context already makes it obvious, but using it twice is completely natural if the speaker wants to stress both actions.

This is an important nuance.

• 썼어 = wore / put on / wore it
• 쓰고 있었어 = was wearing / had been wearing

Here:

• 쓰다 = to wear (for things like hats, glasses, masks)
• -고 있다 = be doing
• -고 있었어 = was doing / had been doing

So 마스크를 계속 쓰고 있었어 means the speaker was in the state of wearing the mask for some period of time.

That sounds more natural here than 썼어, because the sentence is describing an ongoing situation, not just the moment of putting the mask on.

In Korean, different clothing/accessory items use different verbs for to wear.

For example:

• 쓰다 = wear on the head/face
  
  • 모자를 쓰다 = wear a hat
  • 안경을 쓰다 = wear glasses
  • 마스크를 쓰다 = wear a mask
• 입다 = wear clothes
• 신다 = wear shoes
• 끼다 = wear/put on rings, gloves, etc.

So 마스크를 쓰다 is the normal Korean expression.

Because 마스크 is the object of 쓰다.

• 마스크를 쓰다 = to wear a mask

The particle 를 marks the direct object.
So:

• 마스크를 계속 쓰고 있었어 = I was 계속 wearing the mask

If you used 마스크가, the grammar and meaning would be different, and it would not fit this verb pattern.

In this sentence, yes, it is giving a reason:

• 콧물이 계속 나와서 마스크를 계속 쓰고 있었어
• Because my nose kept running, I kept wearing a mask.

But -아서/어서 can also simply connect actions as and then depending on context.

Here, the logic clearly shows cause and effect:

1. nose kept running
2. therefore mask kept being worn

So the most natural reading is because.

Yes. The ending -었어 is informal/casual speech, often used with friends, family, or people you are close to.

The polite version would be:

• 콧물이 계속 나와서 마스크를 계속 쓰고 있었어요.

Same meaning, just more polite.

No, not naturally.

Because of 쓰고 있었어, the meaning is I was wearing it continuously, not I kept putting it on again and again.

If you wanted to say I kept putting on a mask repeatedly, Korean would use a different structure. This sentence describes a continued state, not repeated separate actions.

Yes.

• 콧물이 나서 = because I had a runny nose / because mucus came out
• 콧물이 계속 나와서 = because my nose kept running

Adding 계속 makes the situation feel more persistent and ongoing. It suggests the problem did not stop, which matches the second half:

• 마스크를 계속 쓰고 있었어 = I kept wearing a mask

So the whole sentence has a strong ongoing situation feeling.