27:Biogas is made from a mixture of methane (CH4) and some other gases arising from the decomposition of organic matter

28:Yes

29:Because it made from natural ingredients

30:it is a renewable source

31:solar energy will be used to solve the problem by we

32:a hydropower station will be built in that arena in the next year by we

33coal will be replaced by another renewable source by we

34:solar power will be used to heat the water

35:this bicycle is her

36:they will be learning English this time tomorrow

37 solar energy will be used in the future by many contry
38how long dose it take him to go to school on foot?

39people won't use flying car until the year 2050

40 I thing biogas is cheap and abundant