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: Cows are social animals. 
Sentence2: when a cow moves, chemical energy is converted to mechanical energy.
[EX A]: Cows

[EX Q]: Sentence1: Fractures heal when osteoclasts form new bone. 
Sentence2: Fractures A fracture is a broken or cracked bone.
[EX A]: Fractures

[EX Q]: Sentence1: Mating is generally preceded by courtship. 
Sentence2: Males and females mix only to mate.
[EX A]:
Mating