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: Clear mucus is secreted before ejaculation to neutralize acidic urine remaining in the urethra.

Answer: What is secreted before ejaculation to neutralize acidic urine remaining in the urethra?


Question: Amount of salt are aquatic biomes often classified.

Answer: How are aquatic biomes often classified?


Question: There are four types of bosons.

Answer:
How many types of bosons are there?