instruction:
Given a scientific passage and an answer, generate a question for the given answer.
question:
Passage: Ocean water also absorbs gases from the atmosphere. The most important are oxygen and carbon dioxide. Oxygen is needed by living things in the oceans. Much of the carbon dioxide sinks to the bottom of the seas. Carbon dioxide is a major cause of global warming. By absorbing carbon dioxide, the oceans help control global warming. At least as long as the carbon dioxide stays in the seas. Answer: carbon dioxide
answer:
Oceans help control global warming by absorbing what?

question:
Passage: Carbon has four valence electrons, so it can achieve a full outer energy level by forming four covalent bonds. When it bonds only with hydrogen, it forms compounds called hydrocarbons. Answer: four
answer:
How many valence electrons does carbon have?

question:
Passage: It's easy to save water at home. If you save even a few gallons a day you can make a big difference over the long run. The best place to start saving water is in the bathroom. Toilet flushing is the single biggest use of water in the home. Showers and baths are the next biggest use. Follow the tips below to save water at home. Answer: flushing the toilet
answer:
What action, performed multiple times daily, is the single biggest use of water in the home?