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: Cows are social animals. 
Sentence2: when a cow moves, chemical energy is converted to mechanical energy.

Answer: Cows


Question: Sentence1: a thermometer is used to measure temperature. 
Sentence2: a thermometer is used to measure heat.

Answer: a


Question: Sentence1: a seismometer is used to measure the strength or magnitude of an earthquake. 
Sentence2: The strength of an earthquake refers to the maximum amplitude of the shaking.

Answer:
earthquake