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66. Hong river is shorter than Nile river. 

67. If they don't study harder, they won't pass the exam. 

68. This house was built for his parents by Nam last year.

69. Because the street was crowded, we didn't go out. 

70. The woman who is singing is my teacher

66. No one in our class studies better than Hung

67. If he doesn't take these pills, he won't be better.

68. A new school will be built next month.

69. Although Lan was tired, she helped her friends with difficult exercises.

70. The woman who is talking to students over there is my new teacher.

66. That restaurant is the best in the city

67. If I had enough money, I could buy that dictionary. 

68. This picture was painted by Mai last night.