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: 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: a seismometer is used to measure the strength or magnitude of an earthquake. 
Sentence2: Seismometer Calibration : Instructions on how to calibrate a homemade seismometer.

Answer: seismometer


Question: Sentence1: heavy rains cause flooding. 
Sentence2: Heavy rain can cause erosion and landslides.

Answer:
cause