5. It is very dangerous to walk alone after 10 pm in that park.

=> B. You mustn’t walk alone after 10 p.m in the park. 

6. Antarctica is colder than any other place in the world.

=> D. Antarctica is the coldest place in the world.

7. Remember to bring the compass: if not we will get lost in the forest.

=> You must bring the compass, if not we will get lost in the forest.

8. Doing morning exercises every morning is good for you.

=> You should do morning exercises every day.

9. My father has a plan to repaint our house before Tet.

=> My farther is going to repaint our house before Tet.

10. I wanted to go. He wanted to stay. (but)

=>  I wanted to go but he wanted to stay.

11. Your arguments are strong. They don’t convince me.

=> Your arguments are strong. They don't convince me.

12. She doesn’t use much suncream. She has very pale skin. (although)

=> She doesn't use much sunsream although she has very pale skin.

13. Would you like to go to Paris? Would you rather go to Budapest? (or)

=> Would you like to go to Paris or go to Budapest?

14. He’s very tired today. He went to bed very late last night. (because)

=> He's very tired today because he went to bed very late last night.

15. Cartoons are colourful and funny: that's why children enjoy watching them. Children enjoy watching cartoons.

=> Children enjoy watching cartoons because they are colourful and funny.

16. . I am going to have a test tomorrow; I can't watch the cartoon. I am going to have a test tomorrow.

=> I am going to have a test tomorrow so I can't watch the cartoon.

17. I haven’t visited my family since 2005. (time) 

=> The last time I vistited my family since 2005.

18. My parents moved to New Zealand in 2010. (lived) 

=> My parents have lived in New Zealandsince 2010.

19. I think that no city is more beautiful than Paris. (most)

=> I think Parisis the most beautifulin the world.

20. The computer was too expensive for me to buy. (enough)

=> I didn't have enough money to buy the computer.

21. She is very shy, so she doesn’t enjoy the party.

=> If she doesn't shy, she will enjoy the party.

22. He began learning English three years ago.

=> He have learnt English for three years.

23. Very few cities in Vietnam are as rich as Da Nang.

=> Da Nang is one of the richest cities in Vietnam. 

24. Although it was noisy, we continued to study our lesson.

=> Despite the noise, we continued to study our lesson.

25. The last time they visited Europe was two years ago.

=>  They haven't visited Europe for two years.

26. Robots are not as intelligent as humans. (than)

=> Humans is more intelligent than robots.

27. How long have you learned English? (start)

=> When did you learn English?

Chúc bạn học tốt

5. You mustn’t walk alone after 10 p.m in the park. 

6. Antarctica is the coldest place in the world.

7. You must bring the compass, if not we will get lost in the forest.

8. You should do morning exercises every day.

9. My farther is going to repaint our house before Tet.

10.  I wanted to go but he wanted to stay.

11. Your arguments are strong. They don't convince me.

12. She doesn't use much sunsream although she has very pale skin.

13. Would you like to go to Paris or go to Budapest?

14. He's very tired today because he went to bed very late last night.

15. Children enjoy watching cartoons because they are colourful and funny.

16. . I am going to have a test tomorrow so I can't watch the cartoon.

17. The last time I vistited my family since 2005.

18. My parents have lived in New Zealandsince 2010.

19. I think Parisis the most beautifulin the world.

20. I didn't have enough money to buy the computer.

21. If she doesn't shy, she will enjoy the party.

22. He have learnt English for three years.

23. Da Nang is one of the richest cities in Vietnam. 

24. Despite the noise, we continued to study our lesson.

25. They haven't visited Europe for two years.

26. Humans is more intelligent than robots.

27. When did you learn English?

chúc bạn học tốt >.<