cho tam giác ABC cân tại A kẻ AH vuông góc với BC a.chứng minh H là trung điểm của BC b. Tính AH,biết AC=5, CH=3

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VI. Mark the letter A, B, C, or D to indicate the correct answer to each of the following questions. 67. The president of the company officially apologised to the local residents........having dumped a large amount of raw sewage in the area. A. about B. with C. at D. for 68. The factory was accused.......having caused higher level of pollution to the environment. A. about B. on C. of D. for 69. We all admire him........having changed both his attitude and behaviours towards the environmental issues. A. about B. for C. with D. at 70. Human activities are also blamed........having contributed to globalwarming. A. for B. on C. at D. with 71. We congratulated him......having invented an energy-saving device. A. for B. at C. about D. on 72. He was criticised....not having put the elephant poachers in jail. A. at B. about C. for D. on 73. His company was punished....not having dumped the rubbish properly. A. by B. for C. about D. because of 74. The city mayor praised all voluntary students......having cleaned the playgrounds for the children. A. for B. because of C. at D. due to 75. He thanked us......having contributed to cleaning the surrounding environment. A. on B. to C. with D. for 76. He was suspected......having received presents from the local companies and ignored their violations of the environmental law. A. about B. on C. of C. for 77. Even when arrested, he denied....cut down that tree. A. has B. having C. have D. have had 78. Those farmers admitted…...having used more chemical fertilisers than needed. A. on B. about C. for D. to 79. He forgot…...promised to cut down on the carbon dioxide emissions into the atmosphere. A. to have B. have C. having D. had 80. I remembered having....off the lights before leaving home. A. switched B. switch C. switching D. switches 81. He regretted not....registered for military service last spring. A. have B. having C. having had D. having done 82. The local residents suspected the authorities......having kept the pollution level secret from the local people. A. about B. on C. of D. for 83. He denied having polluted the environment, ......no one believed him. A. however B. despite C. but D. in spite of 84. Thank you for having.....the information about global warming. A. shared B. sharing C.share D. shares 85. He regretted....killed and eaten several rare species. A. to have B. having C. have D. has 86. His company was fined....dumped tons of toxic waste near the residential area. A. to have B. because of having C. for having D. of having 87. These students were rewarded…...actively taken part in voluntary activities. A. with B. before C. on having D. for having 88. She was praised…..donated a lot of money to the wildlife protectionorganisation. A. for having B. to have C. because of having D. due to having 89. I remember......advised you to stop hunting endangered animals. A. to have B. having C. have D. had 90. The local authorities were blamed…...ignored the pollution issues in the area. A. about having B. on having C. for having D. before having