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.

Sealants can normally last up to ____ years and hold up very well under normal chewing.
five

Rabbits have ____ incisors in the upper jaw where rodents have only two.
four

Adult hemoglobin has two alpha and ____ beta chains.

two