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]: Dashes are ____ times the length of dots.
[A]: three


[Q]: Mollusks have one or ____ hearts.
[A]: two


[Q]: Formal communication has ____ subcategories of communication types.
[A]:
four