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.
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Question: Sentence1: Balance is the ability to sense and maintain body position. 
Sentence2: Another part of the inner ear is used for balance.

Answer: Balance


Question: Sentence1: Batteries are a better source of DC electricity. 
Sentence2: a flashlight requires batteries to produce light.

Answer: Batteries


Question: Sentence1: a breathing mask is used for keeping harmful particles from entering the respiratory system. 
Sentence2: a breathing mask is used for keeping harmful particles from entering the lungs.

Answer:
breathing