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.

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

A: predators
****
Q: Sentence1: Mammalian teeth are important for digestion. 
Sentence2: bats' teeth are important for digestion.

A: digestion
****
Q: Sentence1: nerves can be used to feel heat and pressure on the skin. 
Sentence2: The sensation of feeling heat and pressure on the skin is transmitted electrically.

A:
feel
****