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.

Carbon atoms are tetravalent, and therefore, can have ____ bonding pairs around each carbon atom.
four

Maps have ____ or more bar scales, each in a different unit of measure.
three

Most programmable circuits have at least ____ channels.

two