In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Q: Willow flycatchers have a lifespan of _ to four years.

A: three
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Q: Cats There are thirty _ recognised species of cats and a whole host of subspecies or races.

A: five
****
Q: Spacecraft starting from the surface of Earth has a _ initial speed .

A:
zero
****