Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Pressure and vibration are examples of physical type of stimuli.

Answer: Pressure and vibration are examples of what type of stimuli?


Question: Over 90% of the energy we use comes originally from the sun.

Answer: Over 90% of the energy we use comes originally from what?


Question: Ion channels facilitate(s) the diffusion of ions across a membrane.

Answer:
What facilitates the diffusion of ions across a membrane?