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: if an object in a fluid is more dense than that fluid then that object will sink in that fluid because of gravity. 
Sentence2: Most seeds are more dense than water.

Answer: dense


Question: Sentence1: killing microorganisms in food can be used to extend the shelf life of that food. 
Sentence2: Cooking can be used to extend the shelf life of food.

Answer: be


Question: Sentence1: All oaks are plants. 
Sentence2: oaks are multicellular eukaryotes with cell walls made of cellulose.

Answer:
oaks