We use question tags at the end of statements to ask for confirmation. They mean something like: "Are you okay?" or "Do you think so?" They are very common in English.
Rules for Forming Tag Questions
• The subject in the statement matches the subject in the tag.
• The auxiliary verb or verb to be in the statement matches the verb used in the tag.
• If the statement is positive, the tag is usually negative and vice versa.
Examples:
• He's read this book, hasn't he?
• He read this book, didn't he?
• He's reading this book, isn't he?
• He reads a lot of books, doesn't he?
• He'll read this book, won't he?
• He should read this book, shouldn't he?
• He can read this book, can't he?
• He'd read this book, wouldn't he?
