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

Q: The pressure of a sample of gas is measured with an open-end manometer.

A: The pressure of a sample of gas is measured with an open-end what?
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Q: Stimulation of triglyceride breakdown is the first direct action of growth hormone.

A: What is the first direct action of growth hormone?
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Q: Oxygen has increased in the atmosphere throughout the history of the earth.

A:
What has increased in the atmosphere throughout the history of the earth?
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