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.

[EX Q]: Sentence1: killing microorganisms in food can be used to extend the shelf life of that food. 
Sentence2: Cooking can be used to extend the shelf life of food.
[EX A]: be

[EX Q]: Sentence1: Coral reefs are made up of the accumulated exoskeletons of the coral polyp. 
Sentence2: coral polyps form reefs.
[EX A]: polyp

[EX Q]: Sentence1: skin is used for breathing air by frogs. 
Sentence2: Skin is used for breathing air by something that is eaten by bats.
[EX A]:
air