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]: Variable stars fall into ____ major physical classifications.
[A]: four


[Q]: Female dogs come into heat every ____ months or so.
[A]: six


[Q]: Some seeds can remain dormant for up to ____ years.
[A]:
two