17. If you book tickets early, you can get a discount.

18. When you take part in an eco tour, you learn more about the cultural traditions of the local people and the natural habitat of some rare animals.

19. Cutting down trees or hunting wild animals may upset the ecological balance of an area.

20. Mass tourism may cause numerous problems.

21. I am very much interested in learning more about ecotourism and its benefits.

22. Mass tourism has contributed to the destruction of the environment.

23. A lot of waste from hotels and vehicles is also discharged into the water and air.

24. Tourists enjoy the beauty of wildlife without harming it.

25. Some farmers in the Mekong Delta have attracted hundreds of foreign visitors to their ecological gardens.

26. Our country's natural and cultural potential for ecotourism is well known

27. Eco tours in our country involve mainly travel to natural places.

28. Some tourist areas have suffered from some environmental damage.

29. Ecotourism activities have had some negative impacts on the environment and people in the area.

30. Ecotourism needs to recruit better educated people, so it won't provide more jobs for the local people.