I+II/ 1.C 2. B 3. C 4. D 5. B
III/ 6. C 7. A 8. D 9. A 10. C 11. B 12. D 13. D 14. C 15. C
IV/ 16. limestone 17. cliffs 18. flows 19. characteristics 20. fauna
V/
21. Mr. Ba remembers having sold his fishing boat to invest in the shrimp farm.
22. David mentioned having run his car purely on sunlight for 6 years.
23. Scientists blame urban flooding for having changed wetlands and lakes into residential areas.
24. We praised Thu Trang for having won an award for the achievements of her organization, “Water Wise”.
25. We thanked the international organizations for having transformed the city slums into city parks or green residential areas.
VI/ 26. A 27. C 28. B 29. B 30. D 31. A 32. B 33. D 34. C 35. A
VII/ 36. B 37. A 38. C 39. D 40. C
VIII/ 41. B 42. E 43. D 44. F 45. C
IX/
46. Viet Nam is rich in renewable energy sources, such as solar energy, hydroelectricity, and wind power.
47. Clean technologies have not been used in rural and mountainous areas.
48. Renew able energy is used very little because of a lack of financial investment.
49. Two eco-friendly villages were established in Ha Noi to supply themselves with renewable energy by using green technology.
50. The project has the aim to reduce the carbon footprint, and it will develop in several provinces by the year 2020.