chọn phương án đúng ----- Nội dung dịch tự động từ ảnh ----- B. needn't C. might not stand up. There are a lot of seats available on the bus. A. mustn't D. couldn't 15. You A. couldn't B. mustn't C. needn't D. might not 16. People who use public parks clean after themselves. up B. may C. ought A. must D. might 17. This library book is overdue. I better return it today. A. need B. must C. might D. had 18. Our company provides free advice on the use of our products. You pay us. A. must B. have to C. needn't D. mustn't 19. Whatever come, I will always be by your side. A. must B. may C. could D. need you hand that book, please?" "Sure. Here it is." C. Must = 20. " A. Could B. Should D. May