$1$, For a long time, people have been using water to power machines.
`2`. Solar panels will take the place of the roof a house and sun's energy will be used to heat water.
`3`. We use energy from the sun, the wind and the water.
`4`. Many countries have already been using solar energy
`5`, The earth's fossil fuels are running out
6. We / looking / cheap, clean, effective source / energy / not cause pollution or waste natural resource
We are looking for a cheap, clean, effective source of energy that does not cause pollution or waste natural resource
7. Recently / wind / use / generate electricity
Recently wind has used to generate electricity
8. The sun / supply / all energy / used / grow plants / evaporate water / rain / and / maintain / temperature / planet
The sun supplies all energy used to grow plants and to evaporate water for rain and to maintain tenperature of the planet
9. At present / most / our electricity / come / use / coal, gas, oil or nuclear power
At present, most of our electricity comes from the use of coal, gas, oil or nuclear power
10. Today / water power / mostly / use / generate electricity
Today, water power is mostly used to generate electricity
11. This power / could / provide / sun
This power could be provided by the sun
12. If we / able / collect solar energy / we / be sure / have enough power
If we are able to collect solar energy, we will be sure to have enough power
