Viết lại câu sao cho nghĩa không đổi

Viết lại câu sao cho nghĩa không đổi
1.We will use sources of energy more effectively for our future.
=>sources of energy...
2.They will build a hydro power station in the North of the country next year.
=>A hydro power station...
3.We will develop alternative sources of energy
=>Alternative sources of energy
4.I will turn off the lights when leaving a room or going to bed
=>The lights