Một người đứng trên tháp quan sát của ngọn hải đăng cao 50m nhìn về hướng Tây Nam, người đó quan sát hai lần một con thuyền đang hướng về ngọn hải đăng. Lần thứ nhất người đó nhìn thấy thuyền với góc hạ là 20 độ, lần thứ 2 người đó nhìn thấy thuyền với góc hạ là 30 độ. Hỏi con thuyền đã đi được bao nhiêu mét giữa hai lần quan sát. (làm tròn đến chữ số thập phân thứ hai)

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31. “Don’t forget to phone the office,”she told him. => She reminded................... 32. I’m afraid I haven’t got time to listen to you. => I wish......................... 33. The police has just released John. => John.......................................................................................................... 34. I couldn’t hear them because they were speaking too softly. => They were speaking......... 35. We spent 5 hours getting to London. => It took........ 36. I get to work in 20 minutes. => It .................. 37. It is necessary that this work be finished by Monday. => This work........ 38. It’s a pity I didn’t take my doctor’s advice. => I wish............... 39. The bread is so tale we can’t eat it. => The bread isn’t.......... 40. Who does this bag belong to? => Whose........ 41. My boyfriend is very short-tempered. => My boyfriend loses.......... 42. You can use it as long as you like, and it won’t wear out. => No matter........ ............................................................................................ 43. If the work is finished by lunchtime you can go home. => Get..................................................................................................... 44. How have you been getting on with your enquiries? => How much............ 45. I gave Ted the massage, but he already knew about it. => I needn’t......... 46. The trains couldn’t run because of the snow. => The snow……………………………………………………………… 47. I didn’t arrived in time to see him. => I wasn’t early…………………………………………………………. 48. I’m sorry I was rude to you yesterday. => I apologize…………………………………………………………….. 49. She didn’t hurry, so she missed the train. => If………………………………………………………………………. 50. Barbara is the best tennis-player in the club. => No one…………………………………………………………………