of the verb in the preceding sentence. If the verb is in the present perfect, for example, the tag question uses has or have; if the verb is in a present progressive form, the tag is formed with am, are, is; if the verb is in a tense which does not normally use an auxiliary, like the present simple, the auxiliary is taken from the emphatic do form; and if the sentence has a modal auxiliary, this is echoed in the tag: He has 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? He'd read this book, hadn't he? A special case occurs when the main verb is to be in a simple tense. Here the tag question repeats the main verb, not an auxiliary: This is a book, isn't it? Balanced and unbalanced tags English question tags exist in both positive and negative forms. When there is no special emphasis, the rule of thumb often applies that a positive sentence has a negative tag and vice versa. This form may express confidence, or seek confirmation of the asker's opinion or belief. She is French, isn't she? She's not French, is she? These are referred to as balanced tag questions. Unbalanced tag questions feature a positive statement with a positive tag, or a negative statement with a negative tag; it has been estimated that in normal conversation, as many as 40–50% of tags are unbalanced. Unbalanced tag questions may be used for ironic or confrontational effects: Do listen, will you? Oh, I'm lazy, am I? Jack: I refuse to spend Sunday at your mother's house! Jill: Oh you do, do you? We'll see about that! Oh! Making a stand, are we? Unbalanced tags are also used for guessing, or for a suggestion with let's and shall. In particular, let's is always used with the positive unbalanced form: You have talked him into this, have you? I'll make tea, shall I? Let's start, shall we? Patterns of negation can show regional variations. In North East Scotland, for example, positive to positive is used when no special effect is desired: This pizza's fine, is it? (standard English: This pizza's delicious,