1
is something that can exist or you can do instead of something else.
2
a tall building with sails which turn as the wind blows
3
the process of keeking something in a particular place until is needed
4
a steam to turn a wheel and produce power
5
is power obtained from electricity, coal or water, that makes machines work
6
the air moves
7
a current of air moving across the earth\'s surface
