=>
D/
71. My sister is not old enough to watch horror film.
72. I am going to meet the headmaster tomorrow.
73. Doctors have to work on Sundays.
74. We used to go from Hanoi to Ho Chi Minh city by train.
75. We should give up smoking.
II/
76. She warned me to stay away from THE water.
77. My brother has studied English for 5 years.
78. My hat is different from your hat.
79. No one in the class is more intelligent than Daisy.
80. Her roses is more beautiful than the roses I bought yesterday.
III/
81. The students in class 8B are not as careful as we are.
82. My teacher is a good cook.
83. You had to revise your lessons before the examination.
84. No building in the town is taller than this building.
85. Dick said that box was too heavy so he couldn't lift it then.