In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

Question: What forms when nitrogen and oxygen combine at high temperatures? Answer: nitrogen oxide
Nitrogen oxide form(s) when nitrogen and oxygen combine at high temperatures.

Question: Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of what exist? Answer: equilibrium
Expansion of a gas into a vacuum is irreversible because the external pressure is measurably less than the internal pressure of the gas, and no states of equilibrium exist.

Question: Insulin is made up of how many polypeptide chains? Answer: two
Insulin is made up of two polypeptide chains.