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: Lung disease is America's number ____ killer, responsible for one in seven deaths.

Answer: three


Question: Mollusks have one or ____ hearts.

Answer: two


Question: Dicots have ____ cotyledons.

Answer:
two