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: Sponges are subdivided into ____ classes.

SOLUTION: three

PROBLEM: Every isometry is the composition of one, two, or ____ reflections .

SOLUTION: three

PROBLEM: Natural neon is a mixture of ____ isotopes.

SOLUTION:
three