Inventions

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a set of steps leading from one floor of a building to another, typically inside the building.

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two parts rotate together in which a force is transferred from one to the other.

An inclined plane, is a flat supporting surface tilted at an angle

something that can make and receive calls over a radio frequency

a device used to convert electricity into light, consisting of a source of illumination

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.This can be, for example, to drive nails into wood, to shape metal, or to crush rock.