You must return this book to the library before you borrow another book同义句

问题描述:

You must return this book to the library before you borrow another book同义句
You must return this book to the library before you borrow another book 改为同义句 You ____borrow another book _______you return this book to the library

You _can't___borrow another book __unless_____you return this book to the library