When a doctor gives an injection, he sucks up the medicine with a syringe by the action of ______; a pumping machine uses ______ to move water from a low place to a higher place

When a doctor gives an injection, the air inside the syringe is expelled when the piston is pushed down, and then when the piston is lifted upward, the volume inside the syringe increases, the air pressure inside the tube decreases, and the medicine is pressed into the syringe under the action of the external atmospheric pressure.

Pumping is through the piston upward or impeller rotation to make the pumping machine above the water surface of the air pressure decreases, the water in the outside world under the action of atmospheric pressure, was pressed up, the use of atmospheric pressure.

The answer is: atmospheric pressure; atmospheric pressure.