なくてもいいです and なければなりません


  1. My grammar book says:

> Verb/Adjective/Na-Adjective+なくてもいいです

Is it OK to use

> Noun+なくてもいいです,

like:

> 明日でなくてもいいです

  2. My grammar book also says:

> Verb/Noun+なければなりません

Is it OK to use

> Adjective/Na-Adjective+なければなりません,

like:

> 高くなければなりません
>
> きれいでなければなりません



  1. Yes, it is ok, but as you did in your example, one needs to insert で between the noun and なくてもいいです.

明日でなくてもいいです = It does not have to be tomorrow.

  2. If your book just says "It is ok to use Verb/Noun + なければなりません", it is misleading. With nouns, you need to insert は （or が） or で depending on what you want to say, for the phrase to make sense and be grammatical.

The two sentences below have totally different meanings:

ワインはなければなりません = Wine is definitely needed (in life). = We cannot live without
wine.

ワインでなければなりません = It has to be wine (for a certain occasion or to go with a
certain dish).

And yes, it is ok to use Adjective/Na-Adjective + なければなりません and your examples
are both correct.



  1. Yes, it is ok, but as you did in your example, one needs to insert で between the noun and なくてもいいです.

明日でなくてもいいです = It does not have to be tomorrow.

  2. If your book just says "It is ok to use Verb/Noun + なければなりません", it is misleading. With nouns, you need to insert は （or が） or で depending on what you want to say, for the phrase to make sense and be grammatical.

The two sentences below have totally different meanings:

ワインはなければなりません = Wine is definitely needed (in life). = We cannot live without
wine.

ワインでなければなりません = It has to be wine (for a certain occasion or to go with a
certain dish).

And yes, it is ok to use Adjective/Na-Adjective + なければなりません and your examples
are both correct.

