Whenever scientists carefully measure any quantity many times, they expect that
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most of the measurements will be close but not exactly the same

Which of the following is a cause of the ocean levels periodically rising and then falling?
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the force of gravity from the Moon

This in turn causes the average temperature on Earth to rise. Which of the following observations supports that theory?
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Carbon dioxide in the upper atmosphere absorbs and re-emits heat radiated from Earth's surface.