chissori eobseumyeon chiyakman isseodo yangchireul mos hae.

Because 없다 does not take a direct object the way a verb like 먹다 does.

• 칫솔이 없다 = there is no toothbrush / a toothbrush is absent
• So the noun before 없다 is usually marked with 이/가, not 을/를

That is why 칫솔이 없으면 means if there is no toothbrush.

-으면 / -면 means if.

So:

• 없다 = to not exist / to not have
• 없으면 = if there isn’t / if you don’t have

In this sentence, 칫솔이 없으면 means if there is no toothbrush.

A quick pattern:

• 있다 → 있으면 = if there is / if you have
• 없다 → 없으면 = if there isn’t / if you don’t have
• 가다 → 가면 = if someone goes

Because 치약만 있어도 adds the idea of even if you have only toothpaste.

It has two important parts:

• 만 = only
• -아/어도 = even if / even though

So:

• 치약만 = only toothpaste
• 있어도 = even if there is

Together, 치약만 있어도 means even if you have only toothpaste.

This creates a contrast:

• 칫솔이 없으면 = if there is no toothbrush
• 치약만 있어도 = even if you do have toothpaste, that still doesn’t help enough

So the sentence emphasizes that toothpaste alone is not enough.

만 means only / just.

So:

• 치약만 = only toothpaste
• 물만 = only water
• 나만 = only me

In this sentence, 치약만 있어도 means even if there is only toothpaste.

It limits what is available to just one thing: toothpaste.

It can look confusing at first, but they do different jobs.

• 만 limits the noun: only toothpaste
• 도 is part of the grammar -아/어도, which means even if / even though

So 치약만 있어도 is not only ... also. It is:

• 치약만 = only toothpaste
• 있어도 = even if there is

So the whole phrase means:

even if there is only toothpaste

They are not conflicting; they are stacking two different meanings.

양치를 하다 means to brush one’s teeth.

Here:

• 양치 is a shortened everyday form related to 양치질
• 양치를 하다 literally looks like to do tooth-brushing
• In natural English, we usually translate it as to brush your teeth

So:

• 양치를 못 해 = can’t brush your teeth

This is a very common Korean pattern:

• noun + 하다

For example:

• 공부하다 = to study
• 운동하다 = to exercise
• 양치하다 / 양치를 하다 = to brush one’s teeth

Because 양치(를) 하다 can treat 양치 as the object of 하다.

So:

• 양치를 하다 = to do tooth-brushing
• 양치를 못 하다 = to be unable to do tooth-brushing

In everyday speech, Koreans may also say 양치 못 해 without 를, especially in casual conversation. But 양치를 못 해 is completely normal and clear.

못 해 means can’t do or am/is/are unable to do.

It comes from:

• 못 하다 = cannot do
• 못 해 = casual spoken form

So:

• 양치를 못 해 = can’t brush your teeth

Here 못 expresses inability, not simple refusal.

Compare:

• 양치를 안 해 = doesn’t brush / won’t brush
• 양치를 못 해 = can’t brush

That difference is important.

This is a very common learner question.

• 안 해 = don’t do it / won’t do it
  • focuses on choice, habit, or refusal
• 못 해 = can’t do it
  • focuses on inability or impossibility

In this sentence, 못 해 is used because without a toothbrush, brushing your teeth is not really possible.

So:

• 칫솔이 없어서 양치를 안 해 could sound like I’m not brushing my teeth
• 칫솔이 없어서 양치를 못 해 means I can’t brush my teeth because I don’t have a toothbrush

Korean often leaves out the subject when it is understood from context.

So the sentence does not explicitly say:

• I can’t brush my teeth
• you can’t brush your teeth
• one can’t brush one’s teeth

It just says:

칫솔이 없으면 치약만 있어도 양치를 못 해.

Depending on context, English might translate it as:

• If you don’t have a toothbrush, you can’t brush your teeth even if you have toothpaste.
• If there’s no toothbrush, I can’t brush my teeth even if I have toothpaste.
• If there’s no toothbrush, you can’t brush your teeth with only toothpaste.

Korean often relies on context for this.

못 해 is casual, plain speech.

Speech levels:

• 못 해 = casual
• 못 해요 = polite
• 못 합니다 = formal

So the same sentence could be made more polite:

• 칫솔이 없으면 치약만 있어도 양치를 못 해요.

The grammar and meaning stay the same; only the speech level changes.

Yes, that is very close to the Korean structure.

A more natural English translation would be something like:

• If you don’t have a toothbrush, you can’t brush your teeth even if you have toothpaste.
• Without a toothbrush, you can’t brush your teeth with just toothpaste.

The Korean sentence is built in a very logical way:

1. 칫솔이 없으면 = if there is no toothbrush
2. 치약만 있어도 = even if there is only toothpaste
3. 양치를 못 해 = you can’t brush your teeth

Because 있어도 adds a concessive meaning: even if.

Compare:

• 치약만 있으면 = if you have only toothpaste
• 치약만 있어도 = even if you have only toothpaste

The sentence is saying that toothpaste is not enough to change the result. Even with toothpaste, brushing still cannot happen because the toothbrush is missing.

So 있어도 is better here because it highlights:

that condition still doesn’t help

Both are possible in real Korean.

• 양치하다
• 양치를 하다

Both mean to brush one’s teeth.

The version in your sentence uses the noun + 하다 pattern with the object marker:

• 양치를 못 해

That is very natural in speech.

You may also hear:

• 양치 못 해
• 양치질 못 해
• 양치질을 못 해

These are all related and natural, though the nuance and level of formality may vary a little.

It can work as a general statement, and that is probably how most learners will read it.

It expresses a general truth:

If there is no toothbrush, you can’t brush your teeth, even if you have toothpaste.

Korean present tense often covers this kind of general fact.

Depending on context, it could also describe a current situation:

There’s no toothbrush, so I can’t brush my teeth even though I have toothpaste.

Korean often leaves that interpretation to context.