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: Photons have momentum but ____ mass or electrical charge.

SOLUTION: no

PROBLEM: Most soils have ____ major horizons.

SOLUTION: five

PROBLEM: Mammals fall into ____ groups that differ in the way they use the amniotic egg.

SOLUTION:
three