3 Fill in: must, mustn't, can, can't, needn't, or have to. 1 A: Would you like to come out with us tonight? B: Oh, I can't. I have to study for my exams. 2 A: You mustn’t feed the animals in the zoo. B: I'm really sorry. 3 A: Guess what! I've just won a holiday to Bali. B: No way! You must be joking. 4 A: I'm not feeling well. B: You must see a doctor. 5 A: Look! It's Frank. B: It can’t be. He said he was staying in tonight. 6 A: This article says people are wasting far too much electricity. B: That's why we must all try to save energy in the home. 7 A: You can go now if you want to. B: Thanks. See you tomorrow. 8 A: How about a game of chess? B: Sorry, but I have to finish my homework first. 9 A: Would you like me to pick you up later? B: No, you needn’t bother. I'll get the bus. 10 A: Excuse me, sir. You mustn’t use your mobile phone in here. B: Oh, I'm sorry.