1) what is necessary to do work? a) wheel b) energy c) axle d) screw 2) what is useful for moving things? a) inclined plane b) screw c) wheel and axle d) wedge 3) where does radiation come from? a) stars b) the moon c) mars d) the sun 4) what do you use to lift heavy things? a) lever b) wedge c) screw d) pulley

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