1. In opposite to fans, wind **turbines** use wind to produce energy.
2. We cannot think fossil fuels will last **forever**.
3. The most common type of clean energy is the **solar** power.
4. Nowadays **demand** for organic food is increasing.
5. Energy is the ability to do work. It can take a **variety** of forms.
6. Once we use up fossil fuels, they're gone **forever**.
7. Fossil fuels are nonrenewable and cannot be **replenished** easily.
8. Energy from fossil fuels is **harmful** to the environment.
9. Wind turbines **convert** the kinetic energy in the wind into mechanical power.
10. Solar energy is produced by the **radiation** that reaches the earth.
11. Clean energy is renewable. It is made from **resources** that can be replaced.
12. Solar energy can be **converted** into other forms of energy.
13. Different types of **materials** might also be used in building the houses.
14. Solar energy can be used in **generating** electricity to provide power for houses.
15. Shiny **panels** on the roofs of buildings collect heat by absorbing sunlight.