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: Chordates have a complete digestive system and a closed circulatory system. 
Sentence2: animals with jaws have a complete digestive system and a closed circulatory system.

Answer: circulatory


Question: Sentence1: With a spatula, fold in flour mixture. 
Sentence2: a sifter is used for separating flour.

Answer: flour


Question: Sentence1: Populations Populations are subsets of a species. 
Sentence2: Gene flow occurs when individuals move into or out of a subset of a species.

Answer:
species