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: All life relies on a relatively narrow range of pH, or acidity. 
Sentence2: humans rely on a relatively narrow range of acidity.
[EX A]: acidity

[EX Q]: Sentence1: Macroevolution is more than repeated rounds of microevolution. 
Sentence2: evolution over geologic time above the level of the species is more than repeated rounds of microevolution.
[EX A]: microevolution

[EX Q]: Sentence1: Viruses infect and live inside the cells of living organisms. 
Sentence2: viruses infect and live inside the cells of humans.
[EX A]:
Viruses