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: if soil is permeable then water easily flows through that soil. 
Sentence2: The increase in permeability is caused by the formation and expansion of ice in the soil.
[EX A]: permeable

[EX Q]: Sentence1: Macroevolution occurs over geologic time above the level of the species. 
Sentence2: adding new genes with special capability occurs over geologic time above the level of the species.
[EX A]: above

[EX Q]: Sentence1: breaking apart rocks can cause debris. 
Sentence2: Sledge hammers can be used to break especially hard ledges of rock.
[EX A]:
breaking