sonmogi apaseo mauseureul orae mos sseoyo.

아파서 comes from 아프다 meaning to hurt / to be painful.

The ending -아서 / -어서 often means:

• because
• so
• sometimes just connects two actions smoothly

So 손목이 아파서 means because my wrist hurts or my wrist hurts, so...

In this sentence:

• 손목이 아파서 = because my wrist hurts
• 마우스를 오래 못 써요 = I can’t use the mouse for long

So the whole sentence is structured as:

[reason] + [result]

Korean very often puts the reason first.

Korean often omits possessive words like my, your, or his/her when the owner is obvious from context, especially with:

• body parts
• family members
• personal belongings in clear situations

So 손목이 아파서 naturally means:

• because my wrist hurts

even though 내 is not stated.

If you say 내 손목이 아파서, it is still grammatically correct, but it can sound more explicit than necessary unless you want emphasis or contrast.

Here, 손목이 uses the subject marker 이/가.

That is because 손목 is the thing that is hurting:

• 손목이 아프다 = the wrist hurts

So 손목 is the subject of 아프다.

A useful pattern to remember is:

• 머리가 아파요 = my head hurts
• 배가 아파요 = my stomach hurts
• 손목이 아파요 = my wrist hurts

Even though English often says my wrist hurts, Korean typically marks the body part itself as the subject.

마우스를 is:

• 마우스 = mouse
• 를 = object marker

The verb 쓰다 here means to use, so the thing being used is the direct object.

So:

• 마우스를 쓰다 = to use a mouse

That is why 마우스를 appears in the sentence.

오래 is an adverb meaning for a long time or long in duration.

So:

• 마우스를 오래 못 써요 = I can’t use the mouse for long

A very common learner mistake is confusing 오래 with old.
But here 오래 does not mean old. It means for a long time.

Compare:

• 오래 기다렸어요 = I waited a long time
• 오래 공부했어요 = I studied for a long time
• 오래 못 써요 = I can’t use it for long

못 + verb means cannot / be unable to do something.

So:

• 못 써요 = cannot use

In this sentence, it means the speaker is unable to use the mouse for long because of wrist pain.

This is different from 안 써요:

• 안 써요 = do not use / choose not to use
• 못 써요 = cannot use / am unable to use

So here 못 is important because the problem is ability, not choice.

This is a very common question.

The dictionary form is 쓰다.
When you make it into the polite present form:

1. remove 다 → 쓰
2. add -어요
3. 쓰 + 어요
4. this contracts to 써요

So:

• 쓰다 → 써요

This is normal and very common.

Examples:

• 쓰다 → 써요
• 크다 → 커요
• 예쁘다 → 예뻐요

Here, 쓰다 means to use.
Be careful, because 쓰다 can also mean other things in different contexts, such as:

• to write
• to wear (some items, depending on context)

But with 마우스를, it clearly means to use.

Not if you want the same meaning.

• 마우스를 오래 안 써요 = I don’t use the mouse for long / I choose not to use it for long
• 마우스를 오래 못 써요 = I can’t use the mouse for long

Because the sentence includes 손목이 아파서 (because my wrist hurts), the natural choice is 못 써요, since the speaker is talking about a physical limitation.

Yes, 쓰다 is very natural here.

• 마우스를 쓰다 = to use a mouse

You could also say:

• 마우스를 오래 사용할 수 없어요

That means something like I can’t use the mouse for long, and it is grammatically fine. But it sounds:

• more formal
• more written
• less conversational

In everyday spoken Korean, 못 써요 sounds more natural and simpler.

The sentence follows a very common Korean pattern:

손목이 아파서 마우스를 오래 못 써요.

Breakdown:

• 손목이 = wrist + subject marker
• 아파서 = because it hurts
• 마우스를 = mouse + object marker
• 오래 = for a long time
• 못 써요 = cannot use

So the structure is:

[reason] + [object] + [adverb] + [verb]

More literally, it feels like:

Because my wrist hurts, the mouse for a long time I can’t use.

That is why Korean sentences often feel back-loaded to English speakers: the main verb comes at the end.

못 써요 is in the polite informal style, often called 해요체.

It is appropriate for:

• everyday conversation
• speaking politely to most people
• neutral situations

Related styles would be:

• 못 써 = casual / plain spoken
• 못 씁니다 = formal polite

So the same sentence could become:

• 손목이 아파서 마우스를 오래 못 써. = casual
• 손목이 아파서 마우스를 오래 못 씁니다. = formal

The version in your sentence, 못 써요, is a very common and natural everyday polite form.