We must obey the librarian there.

We must abide by the library rules.

We must abide by the rules of the library.

You are in the library. You must obey the rules of the library. You can't smoke. You can't dirty the floor.

When you get to the library, you must obey the rules of the library. You can't smoke and throw things on the floor.

You must abide by the regulations of the library.

You must obey the rules of the library.

You can't talk loudly in the library.

You are not allowed to talk loudly in the library.

We must keep quiet in the library, so you can't talk.

We must keep quiet in the library, so you can't talk.

7. Do you have to? Keep quiet. You must keep quiet.

You must return the book on time.

You must return the borrowed books to the library on time.

When you finish reading this book, you must put it back on the right shelf.

When you finish reading it, you must put it back on the right shelf.

You can't draw or write anything on this page.

Don't scribble on the book.