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: Speciation events are thus examples of macroevolution. 
Sentence2: Speciation events occur over geologic time above the level of the species.
[EX A]: Speciation

[EX Q]: Sentence1: Ozone depletion results in higher levels of UV radiation reaching Earth. 
Sentence2: less ozone means more ultraviolet light.
[EX A]: Ozone

[EX Q]: Sentence1: Populations of viruses do not grow through cell division because they are not cells. 
Sentence2: Viruses are parasites of cells.
[EX A]:
cell