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 no mass and ____ electrical charge.

SOLUTION: no

PROBLEM: Some airports have ____ parallel runways.

SOLUTION: two

PROBLEM: Statistics show that one out of every ____ people has a mental illness.

SOLUTION:
four