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Cho tam giác nhọn ABC nội tiếp đường tròn ( O ; R ) Hai đường cao AD BE ( D thuộc BC E thuộc AC ) lần lượt cắt đường tròn (O) tại các điểm thứ hai là M và N -Cho (O) và dây AB cố định Chứng minh rẳng độ dài bán kính đường tròn ngoại tiếp tam giác CDE luôn không đổi khi điểm C di chuyển trên cung lớn Ai giúp với ạ em đang cần gấp
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37. My father (not/ play)________ any sport since last year. 38. We (never/watch) ________that television program before. 39. My wife and I ________(travel) by air many times. 40. I (have read)________ that novel by Hemingway several times before. 41. We (not/plan)________ our holiday yet. 42. I (see) ________ such a beautiful girl before. 43. They (not give)________ their decision yet. 44. I (read)________ such a good novel before. 45. My family (own)________ this farm since 1990. 46. I (lose)________ my keys, so I can't open that door. 47. John (leave)________ for Brazil this morning. 48. It is a long time since we last (meet)________ . 49. We (study) ________a very hard lesson the day before yesterday. 50. My wife and I (travel)________ to Mexico by air last summer. 51. She (finish) ________not yet ________ doing her homework. 52. He (begin)________ to study English when he was 5 years old. 53. Martin (cycle)________ for 50 miles on scenic routes three weeks ago. 54. Yesterday I (see)________ you talking to a stranger. 55. Jane (write)________ many books about Chinese culture. 56. My parents (get)________ married 20 years ago. 57. ________ you already (wash) ________your car? 58. He (be) ________at his computer for seven hours. 59. He ________ just (come) ________back. 60. We (postpone)________ our journey to the beach because it (rain)________. 61. ________ You (have)________ breakfast this morning? - Yes, I have. I (eat)________ bread and eggs. 62. He (visit)________ her uncle last year. 63. We (celebrate)________ a big festival last year. 64. The policeman (show)________ me the way to the railway station. 65. She (drink)________ some apple juice yesterday. 66. Alan (not see)________ Paul at school. 67. Carol (bring)________ her new laptop to school. 68. The baby (cry)________ all night long. 69. My brother (can)________ swim when he (be)________ four. 70. Charles (prepare)________ a nice dinner. 71. The children (eat)________ a cheese sandwich. 72. ________ you (sit).________ next to Mary? 73. There (be)________ a lot of people at the match. 74. The children (play)________ football after school. 75. Peter (forget)________ my birthday. 76. I (do)________ all the housework. The flat is really clean now. 77. He (write)________ a novel for two years. 78. I (never meet)________ this girl before. 79. My brother (leave)________ home for 10 years. 80. I (not see)________ my close friend since 2013. 81. My mother (buy)________ this bike since last week. 82. Peter (never see)________ a zebra before. 83. Nga (be)________ to England for 3 days. 84. They (travel)________ around the world once. 85. The teacher (tell)________ this story three times. 86. Where________ you (go)________ last summer holiday? 87. Mai (buy)________ a new dress last week. 88. She (eat)________ this kind of pizza twice. 89. Mr. Quang (teach) ________ Maths in this school since he (graduate)________ in 1985. Giải hết nha

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