Anh chị nào làm bài test này giúp em với ạ

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