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: a flashlight requires a source of electricity to produce light. 
Sentence2: Flashlights provide the safest emergency lighting source.

SOLUTION: flashlight

PROBLEM: Sentence1: an image in a mirror is formed by reflecting light. 
Sentence2: mirrors can be seen with our eyes.

SOLUTION: mirror

PROBLEM: Sentence1: Abuse means causing intentional pain or harm. 
Sentence2: Aggression is behavior that is intentionally abusive.

SOLUTION:
Abuse

