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

Q: Reptiles typically reproduce sexually.

A: How do reptiles typically reproduce?
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Q: You call materials that have high resistance to electric current electric insulators.

A: What do you call materials that have high resistance to electric current?
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Q: Electrons in inner shells are called core electrons.

A:
Electrons in inner shells are called what?
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