B.

1. They used stone and mud to buy the house.

2. Because there are skylights-windows in the roof to let light in- so we save electricity.

3. Because we don't want to damage the environments.

4. We can see lots of local wildlife.

C.

I. 

1. Whuy was Hoa absent from class yesterday?

2. Although I like cartoons, I don't watch them much.

3. I have never talked to a foreigner before.

4. My sister will be seventeen next week.

Bài dưới là viết văn, nghe(ko cần lam ạ)

CHÚC HỌC TỐT!!!!

1. They used stone and mud to build the hotel

2. The skylights- windows let light in, so they save energy

3. Because they don't want to damage the environment

4. I can see lots of locak wildlife

C. 1. Why was Hoa absent from class yesterday?

2. Although I like cartoons, I don't watch them much

3. I have n't talked to a foreigner before

4. My sister will be seventeen years old next week