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: Hoatzin has typical foot with ____ toes forwards and one backwards.

A: three
****
Q: Babies start swimming lessons as young as ____ weeks old.

A: four
****
Q: Some scholars question the existence of the first ____ emperors.

A:
nine
****