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.

[EX Q]: Marshes are shallow wetlands less than ____ meters deep.
[EX A]: two

[EX Q]: Water consists of ____ hydrogen and one oxygen atom.
[EX A]: two

[EX Q]: Most rivers overflow once every ____ years.
[EX A]:
two