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: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Life without protein is impossible.

SOLUTION: proteins

PROBLEM: Sentence1: friction causes the temperature of an object to increase. 
Sentence2: Friction causes the temperature of a toy to increase.

SOLUTION: causes

PROBLEM: Sentence1: a light bulb is used for seeing in the dark. 
Sentence2: Electricity can be converted in to light using light bulbs, and even heat by using heating coils.

SOLUTION:
bulb