Complete the second sentence so that it has a similar meaning to the first

Complete the second sentence so that it has a similar meaning to the first
1.Natural gas is cheaper and less polluting than coal
Coal is
2.We are trying to find cheap and clean,and effective sources of energy
We are looking
3.Will solar and wind replace fossil fuels within 20 years?
Will fossil fuels
4.This is the second time I have visited Yaly hydroelectric power plant 
I have
5.They built the first hydroelectric power plant at Niagara Falls in 1879
The first hydroelectric power plant
6.It's a good idea to switch off electrical appliances when they are not in use
You
7.Although coal is the most polluting of fossil fuels ,it is still the largest source of energy worldwide
Despite
8.Biogas will be used for fuel in homes and for transport 
people
các bạn giải nhanh giúp mình nhé ,mình tick cho 5 sao