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

A: Humans
****
Q: Sentence1: wind is used for producing electricity. 
Sentence2: Wind is caused because of pressure differences in the atmosphere.

A: wind
****
Q: Sentence1: fanning a fire increases the oxygen near the fire. 
Sentence2: On the other hand, air is the element that fans the flames of fire.

A:
fanning
****