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

In a carbon triple bond, three pairs of electrons are shared.
In a carbon triple bond, how many pairs of electrons are shared?

If two populations do not mate and produce fertile offspring, separate species result.
If two populations do not mate and produce fertile offspring, what results?

Human beings is/are the main cause of recent global warming.
What is the main cause of recent global warming?