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.

Sentence1: Humans have collected and grown mushrooms for food for thousands of years. 
Sentence2: humans have collected and grown porcinis for thousands of years.
Humans

Sentence1: Absorption of nutrients occurs mainly in the small intestine. 
Sentence2: The small intestine is the main place where food absorption occurs.
intestine

Sentence1: Acidity is measured with a pH meter or with pH paper strips. 
Sentence2: All life relies on a relatively narrow range of something you can measure with paper strips.

paper