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.

Q: Nitric oxide serves ____ main functions in the body.

A: three
****
Q: Environmentalists warn that ____ turtle species are in severe decline from over-exploitation.

A: six
****
Q: Spiders usually have a round or oblong body and ____ legs.

A:
eight
****