Complete the dialogue with: must, mustn't, have to, don't have to, don't need to, might. Give reasons for your choices. A: Hi, John. What are you doing here? B: I want to sign up for an exercise class. My doctor says I 1) .................... lose some weight. A: You 2) .................... lose a lot. You should try the aerobics class that I teach. B: I know I 3) .................... do some exercise, but perhaps your aerobics class is too much for beginners like me. A: You 4) .................... give up so easily, John. Try one lesson. You 5) .................... carry on if you don't like it. B: Mmm, I'm not sure. A: You never know! You 6) .................... enjoy it!