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

Negative growth rate results when birth rates fall even lower than death rates.
What results when birth rates fall even lower than death rates?

You call materials that have high resistance to electric current electric insulators.
What do you call materials that have high resistance to electric current?

The term "vapor" refers to the gas phase when it exists at a temperature below boiling temperature.
The term "vapor" refers to the gas phase when it exists at a temperature below what?