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: Some trees are maples. 
Sentence2: planting maples has a positive impact on an ecosystem.

Answer: maples


Question: Sentence1: Caverns Secrets are hidden in caves. 
Sentence2: hidden caves are formed by carbonic acid in groundwater seeping through rock and dissolving limestone.

Answer: are


Question: Sentence1: Gene flow occurs when individuals move into or out of a population. 
Sentence2: Geographic subdivision decreases how fast individuals move into or out of a population.

Answer:
individuals