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]: Green energy comes in ____ basic forms.
[A]: two


[Q]: International mail consists of ____ categories of mail.
[A]: three


[Q]: Baleen whales have ____ and toothed whales have one.
[A]:
two