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: The action of flushing the toilet, performed multiple times daily, is the single biggest use of water in the home.

Answer: What action, performed multiple times daily, is the single biggest use of water in the home?

Question: Producing sperm and secreting testosterone are the main functions of male reproductive system system.

Answer: Producing sperm and secreting testosterone are the main functions of what system?

Question: Lymph vessels are like blood vessels, except they move lymph instead of blood.

Answer:
Lymph vessels are like blood vessels, except they move what instead of blood?