Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Q: Muscle groups are controlled by the motor cortex .

A: Muscle groups are controlled by what mechanism?
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Q: The cerebellum of the brain lies under the cerebrum and behind the brain stem.

A: What part of the brain lies under the cerebrum and behind the brain stem?
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Q: The size of the solute particles determines the rate of dissolving.

A:
The size of the solute particles determines the rate of what?
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