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: All life relies on a relatively narrow range of pH, or acidity. 
Sentence2: humans rely on a relatively narrow range of acidity.

Answer: acidity


Question: Sentence1: threatening behavior by predators causes a porcupine to extend its quills. 
Sentence2: Fishers are one of the few specialized predators on porcupines.

Answer: predators


Question: Sentence1: Hermit crabs use the shells of dead snails for homes. 
Sentence2: Hermit crabs are scavengers for dead snails.

Answer:
Hermit