Нужно правильно решить и написать

Peter must return the book to the library.
We all want to read it.
She may not call the doctor again unless she feels worse.
Can we do the exercise at once?-Yes, you can do it at once.
You need not have bought this meat: we have everything for dinner.
I may not go out today: it is too cold.
By the end of the week, I must have finished writing my book.