Choose the sentence (A, B, C or D) that is closest in meaning to the root sentence. 46. People should exercise regularly to stay healthy. A. People ought to exercise regularly to stay healthy. B. People have to exercise regularly to stay healthy. C. People mustn't exercise regularly to stay healthy. D. People could exercise regularly to stay healthy. 47. Perhaps Nga knows the answer. A. Nga should know the answer. B. Nga could know the answer. C. Nga would know the answer. D. Nga may know the answer. 48. The best thing for Nick to do is calm down. A. Nick must calm down. B. Nick shouldn't calm down. C. Nick would calm down. D. Nick has to calm down. 49. Phong wants a cup of coffee. A. Phong likes enjoying a cup of coffee. B. Phong should have a cup of coffee. C. Phong would like a cup of coffee. D. Phong would have a cup of coffee. 50. It's dangerous to wash your hair when you have a headache. A. You should wash your hair when you have a headache. B. You shouldn't wash your hair when you have a headache. C. You mush wash your hair when you have a headache. D. You will wash your hair when you have a headache.