I'd like to understand the pattern "verb+nai+to(+ne)"


In the sentence:

> 掟は ちゃんと教えないとね (okite wa chanto oshienai to ne)  
>  [You must be taught the rules properly.]

I'd like to understand this pattern of using verb-nai-to(-ne). Thanks.




If you want to express obligation in Japanese, like _X has to do Y_ or _X must
do Y_ in English, you have to say something like _if X doesn't do Y, it's
bad_. The first part of that structure, the _if X doesn't do Y_ is expressed
by conjugating the verb in three possible ways. One of them is ない + と. For
example, 教えないと means _if X doesn't teach_. Then you'd have to add something
like いけない or ならない for the second part of the structure, the _it's bad_ part.
But in colloquial speech it's usually omitted. So saying _I have to go_ is
exactly the same as _if I don't go_.

[Here](http://www.guidetojapanese.org/learn/grammar/must) you have a more
detailed explanation.




If you want to express obligation in Japanese, like _X has to do Y_ or _X must
do Y_ in English, you have to say something like _if X doesn't do Y, it's
bad_. The first part of that structure, the _if X doesn't do Y_ is expressed
by conjugating the verb in three possible ways. One of them is ない + と. For
example, 教えないと means _if X doesn't teach_. Then you'd have to add something
like いけない or ならない for the second part of the structure, the _it's bad_ part.
But in colloquial speech it's usually omitted. So saying _I have to go_ is
exactly the same as _if I don't go_.

[Here](http://www.guidetojapanese.org/learn/grammar/must) you have a more
detailed explanation.

