TASK DEFINITION: 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.
PROBLEM: Sealants can normally last up to ____ years and hold up very well under normal chewing.

SOLUTION: five

PROBLEM: Cells contain ____ families of small organic molecules.

SOLUTION: four

PROBLEM: Scientists divide the mosses into ____ groups .

SOLUTION:
eight