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: Sexual maturity is between ____ and six years of age.

Answer: three


Question: Cytochrome oxidase consists of two cytochromes and ____ copper atoms.

Answer: two


Question: Sheep have ____ skin pouches, or scent glands.

Answer:
three