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: An organism can gain energy by assimilation or absorption of food. 
Sentence2: Organisms require food for growth.

A: food
****
Q: Sentence1: Marine dolphins are endangered by fishing nets, speedboats, and pollution. 
Sentence2: dolphins live mainly in shallow coastal waters.

A: dolphins
****
Q: Sentence1: the vanes rotating in an electric fan causes air to move. 
Sentence2: fan speed is adjustable.

A:
fan
****