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: Mammals that are viviparous are called therian mammals. 
Sentence2: Mouse-sized viviparous mammals evolved by Jurassic times.

A: Mammals
****
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.

A: Evaporation
****
Q: Sentence1: Elephants are the largest land animals. 
Sentence2: lungs are used for breathing air by elephants.

A:
Elephants
****