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]: Brook stickleback have prominent mouths, large eyes and ____ to six spines on their backs.
[A]: four


[Q]: Respiratory therapists complete two to ____ years of education.
[A]: four


[Q]: Elephants get ____ sets of teeth over their lifetime.
[A]:
six