J. Have you? And wasn’t it? are Question Tags (= mini-questions that we often put on the end of a sentence in spoken English). In question tags, we use an auxiliary verb (have/ was/ will etc.)
a. We use do/ does/ did for the present and past simple. (e.g. Julie plays the piano, doesn’t she? Well, yes, but not very well.)

J1. Normally we use a negative question tag after a positive sentence. (e.g. Ann will be here soon, won’t she?)
a. Ann won’t be late, will she?
b. Notice the meaning of yes and no in answer to a negative sentence. (e.g. You’re not going out today, are you? Yes. (= Yes, I am going out) or No. (= No, I am not going out))

J2. The meaning of a question tag depends on how you say it. If your voice goes down, you are not really asking a question; you are only inviting the listener to agree with you. (e.g. It’s a nice day, isn’t it? Yes, beautiful.)
a. But if the voice goes up, it is a real question. (e.g. You haven’t seen Lisa today, have you? (= Have you by chance seen Lisa today?) No, I’m afraid I haven’t.)
b. can use a negative sentence + positive tag to ask for things or information, or to ask somebody to do something. The voice goes up at the end of the tag in sentences like these. (e.g. You haven’t got a pen, have you? Yes, here you are.)

J3. After Let’s … the question tag is shall we. (e.g. Let’s go for a walk, shall we? (the voice goes up))
a. After Don’t …, the question tag is will you. (e.g. Don’t be late, will you?) (the voice goes down))
b. After I’m …, the negative question tag is aren’t I? (= am I not). (e.g. I’m right, aren’t I? Yes, you are.) -ing and to ~ (infinitive)