TASK DEFINITION: Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.
PROBLEM: Sentence1: Combustion-related, motor vehicles, wood burning, open burning, industrial processes. 
Sentence2: Combustion is used to produce heat.

SOLUTION: Combustion-related

PROBLEM: Sentence1: when a hemisphere is tilted away from the sun , that hemisphere receives less direct sunlight. 
Sentence2: Sunlight is delivered in small packets of energy called photons.

SOLUTION: sunlight

PROBLEM: Sentence1: Mass The base unit of mass is the gram. 
Sentence2: A balance measures in grams.

SOLUTION:
gram