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.

[EX Q]: Question: Where are aerofoils found? Answer: birds and airplanes
[EX A]: Birds and airplanes are aerofoils found.

[EX Q]: Question: Which unit is used to express the amount of energy in food? Answer: Calorie
[EX A]: A calorie is used to express the amount of energy in food.

[EX Q]: Question: What involves the reaction of a hydrocarbon with oxygen gas to produce water and carbon dioxide? Answer: combustion reactions
[EX A]:
Combustion reactions involve the reaction of a hydrocarbon with oxygen gas to produce water and carbon dioxide.