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: Green lines represent the boundaries between the ____ hemispheres.

SOLUTION: two

PROBLEM: World population continues to rise, even as a few countries move toward ____ growth.

SOLUTION: zero

PROBLEM: Frictional forces cause the ____ plates to be locked together.

SOLUTION:
two