15. we/buses/use/solar-powered/ten years/ will /in.

<= we will use solar-powered buses in ten years.
16. solar energy/ in the world/ by many countries/ will be used/.

<= solar energy will be used by many countries in the world
17. to another/How/ you travel from/ will/ one place/?
<=how will you travel from one place to another ?
18. to save/ will reduce/ our energy/ the use of electricity/ We/.
=>we will reduce the use of electricity to save our energy.
19. people/ until/ flying cars/ use/ won't/ the year 2050.

=>people won't usr flying car until the year 2050
20. not many / though the film/people/ went to see/ received / it / good reviews/

=> though the film received not many good reviews, people went to see it.