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: Evaporation of sweat uses energy, and the energy comes from body heat. 
Sentence2: Evaporation of sweat uses energy, and the energy comes from exercise.
[EX A]: Evaporation

[EX Q]: Sentence1: Most mammals have hair, or fur, covering their body. 
Sentence2: Most mammals have a body covering for keeping warm.
[EX A]: body

[EX Q]: Sentence1: Tree rings are examined to learn the forest age and growth rate. 
Sentence2: the rings in a tree determined the growth rate of the forest.
[EX A]:
growth