Given a sentence, fill out the missing word with a 'no' or a number (between zero and ten). You should write the numbers with english alphabet, like: four instead of 4.
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Question: Most healthy men experience about three to ____ erections in their sleep each night.

Answer: five


Question: Most people become sick ____ to seven days after infection.

Answer: two


Question: Homozygosity is achieved by crossing ____ hemizygous animals.

Answer:
two