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: a camera is used for recording images. 
Sentence2: a camera is used for recording binary.

Answer: camera


Question: Sentence1: when electricity flows to a light bulb , the light bulb will turn on. 
Sentence2: water pumps can turn on light bulbs.

Answer: bulb


Question: Sentence1: When a compound is unbalanced it becomes unbalanced and unstable. 
Sentence2: Blood pH may become unstable if the rate of breathing is too fast or too slow.

Answer:
unstable