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a region of space where there is no matter or energy
a device that controls the flow of fluids
a chemical element with the symbol V and atomic number 23
a substance that has turned from a liquid into a gas
a quantity that can change
a resistor whose resistance can be changed
a plant part that is eaten as food
the plant life of a region
a machine that moves people or goods from one place to another
a blood vessel that carries blood back to the heart
the process of exchanging air in a closed space
a large chamber in the heart that pumps blood
the second planet from the Sun
animals that have a backbone
relating to animals or their diseases
a repetitive motion back and forth around a central point
a modern constellation in the northern hemisphere, representing a maiden with a sheaf of wheat and featuring the bright star Spica
a scientist who studies viruses
a non-living particle that can infect cells and cause disease
nutrients that your body needs to stay healthy
a vitamin that helps your body absorb calcium and phosphorus
the study of volcanoes
a unit of electrical potential difference
a measure of the "pressure" that pushes electricity through a wire
a tool that measures the voltage between two points in an electric circuit
the amount of space an object takes up
being open to attack or harm