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]: Earth is the third planet from the Sun in our solar system, which includes ____ other planets.
[A]: seven

[Q]: Sponges are subdivided into ____ classes.
[A]: three

[Q]: Calves first start to drink water with their trunks from about ____ months old.
[A]:
three