Task 3. Complete the sentences with must, mustn't, should or shouldn't and the verb in the brackets. 1. You can't use your mobile phone during a test. You your mobile during a test. (use) 2. It isn't a good idea to talk and eat at the same time. You at the same time. (eat) 3. My friend Sandy is really upset today. I think I to her. (talk) 4. People can work for days and not find anythin. very patient. (be)​