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.

Q: Question: What do you call sound that has a wave frequency higher than the human ear can detect? Answer: ultrasound

A: You call sound that has a wave frequency higher than the human ear can detect ultrasound.
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Q: Question: Fires, mainly caused by what, are a natural disturbance in temperate grasslands? Answer: lightning

A: Fires, mainly caused by lightning, are a natural disturbance in temperate grasslands.
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Q: Question: When volume does not change, temperature is proportional to what other property? Answer: pressure

A:
When volume does not change, temperature is proportional to pressure.
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