Use of word No: The book is no more expensive than that one

Dear teachers,

My teacher wrote:

1.The book is no more expensive than that one.
2.If you’re no better, call me.
3. He is no teacher.
Do you think (1), (2)and (3) have the same meaning with:

4.The book isn’t more expensive than that one.
5.If you aren’t better, call me.
6. He is not a teacher.
Thanks
Quoc

They have the same basic meaning, but it is a matterof emphasis.

1.The book is no more expensive than that one.
If you want to emphasise one book v another: “This book is no more expensive than that one”; or “This book isn’t more expensive”.
If you want to compare the book to something else(a cd?): “The book is no more expensive than the cd”.

  1. No better, v Not better.
    “No better” means not any better, not even a little better.
    “Not better” means not completely bettter.

  2. “He is no a teacher”: means he is not a teacher, but it would be used to refer to somebody who thinks he is a teacher, or is trying to teach.