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: Tree-ring dating the 1700 Cascadia earthquake. 
Sentence2: estimating the age of trees can be used in reviewing earthquake history.

Answer: earthquake


Question: Sentence1: Insulin is a hormone that helps cells absorb sugar from the blood. 
Sentence2: the pancreas produces a hormone that helps cells absorb sugar from the blood.

Answer: absorb


Question: Sentence1: Migration is a type of movement that changes population size. 
Sentence2: Movement is thought in motion.

Answer:
movement