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: an animal requires air for survival. 
Sentence2: The Moon has no atmosphere and no air.
[EX A]: air

[EX Q]: Sentence1: freezing means changing from a liquid into a solid by reducing heat energy. 
Sentence2: Water freezes into ice when cooled.
[EX A]: freezing

[EX Q]: Sentence1: DNA contains genetic instructions for proteins, and RNA helps assemble the proteins. 
Sentence2: cells have proteins.
[EX A]:
proteins