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

[EX Q]: Natural resource type of resource is limited in supply and cannot be replaced except over millions of years.
[EX A]: What type of resource is limited in supply and cannot be replaced except over millions of years?

[EX Q]: All life is built around the element carbon.
[EX A]: What element is all life built around?

[EX Q]: Anions are formed by atoms gaining electrons.
[EX A]:
What are formed by atoms gaining electrons?