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

Line graphs are especially useful for showing changes over time.
Line graphs are especially useful for showing changes over what?

Glycolysis is a series of reactions that is common to fermentation and cellular respiration.
What series of reactions is common to fermentation and cellular respiration?

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

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