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: Heterotrophs get food by eating other living things. 
Sentence2: fish eat other living things.

Answer: living


Question: Sentence1: a stopwatch is used to measure time. 
Sentence2: Time can be measured with a clock or watch.

Answer: measure


Question: Sentence1: the emission of sulfur dioxide causes acid rain. 
Sentence2: Ecosystems are damaged by sulfur dioxide.

Answer:
dioxide