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: Carbon atoms are tetravalent, and therefore, can have ____ bonding pairs around each carbon atom.

SOLUTION: four

PROBLEM: Electric power means no gas or oil to spill, and ____ pollution in the air.

SOLUTION: no

PROBLEM: Cancer affects one in ____ individuals.

SOLUTION:
three