Giải giúp em bài tập này với ạ

Practice 2: Choose the best answer (A, B, C complete the föllöwing sentences. 1. You use your mobile phone in the exam. A. oughtn't to 2. My grandparents live in the suburb. Therefore, whenever we visit them, we A. must take take B. mustn't C. don't have to D. shouldn't bus. B. should ...