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]: Babies start swimming lessons as young as ____ weeks old.
[A]: four


[Q]: Hearing is acute by three or ____ weeks and kittens learn to determine what sounds mean.
[A]: four


[Q]: Possums spend the first ____ months of their lives in their mother's pouch.
[A]:
four