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]: Males mature sexually as soon as ____ years of age.
[EX A]: two

[EX Q]: Ligand seeks ____ receptors into binding and mutual phosporylation.
[EX A]: two

[EX Q]: Psychology has ____ faces.
[EX A]:
three