Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
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Question: Fires, mainly caused by lightning, are a natural disturbance in temperate grasslands.

Answer: Fires, mainly caused by what, are a natural disturbance in temperate grasslands?


Question: The bones of the newborn skull are not fully ossified and are separated by large areas called fontanelles.

Answer: The bones of the newborn skull are not fully ossified and are separated by large areas called what?


Question: The element sulfur is released into the atmosphere by the burning of fossil fuels.

Answer:
What element is released into the atmosphere by the burning of fossil fuels?