`77`. They used stone and mud to build the hotel.

- Dẫn chứng (câu 2): We used stone and mud to build the hotel.

`78`. They let light in the windows in the roof to help us to save electricity.

- Dẫn chứng (câu 3): There are skylights - windows in the roof let the light in - so we save electricty.

`79`. Because they don't want to damage the environment.

- Dẫn chứng (câu 5): We don't use chemicals to clean the rooms because we don't want to damage the environment.

`80`. You can see lots of local wildlife in the mountains.

- Dẫn chứng (Câu 6): You walk in the mountains near hotel and see lots of local wildlife.

`81`. You can see the amazing waterfalls, or visit the beautiful caves when enjoy a boat trip on the lake.

- Dẫn chứng (câu 7): Enjoy a boat trip on the lake and see the amazing waterfalls, or visit the beautiful caves.