In this lesson, you'll learn how to say things like "I must do my homework", "my little sister must not lie", etc. I'll be teaching the formal way to do express it, if anyone really wishes I can explain the 'shortcuts' or the informal version.

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Must Not Do

First, we’ll talk about how to say that you must not do something

Conjugation

To conjugate this, you have to conjugate to the -te form of the verb (if you don't know how to do this, don't worry; a lesson on it will be made later). After it's conjugated to the -te form, you than add は followed by either だめ、いけない、Or ならない.

The differences between these three are pretty simple. だめ is a word that means 'bad' or 'no good', and there is not much of a difference between ならない And いけない, other than ならない is normally used for things like set rules that apply to more than one person.

To say something like "You can't eat that", you would use the verb 食べる "to eat", conjugate it to 食べて, and then add はだめ、はいけない、はならない

それを食べてはだめ- You can't eat that (it's bad if you do)

それを食べてはいけない- You can't eat that

それを食べてはならない- You can't eat that (it's a rule that you can't eat that)

Other Examples

車（くるま）に乗（の）ってはならない- You can't ride in the car

そんなことを言（い）ってはダメ- You can't say something like that

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Must Do

Conjugation

Negative te-form (will be covered in the te-form lesson)+は+だめ、いけない、ならない

Negative verb＋と＋だめ、いけない、ならない

Examples

毎日（まいにち）学校に行かなくてはなりません- Must go to school every day

それを食べなくてはいけない- Have to eat that

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I apologize if that was a little hard to follow, and I know that it has some grammar points that people may not know. If you have any questions, you can't comment and I can try to answer.

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