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: creating paper requires cutting down trees. 
Sentence2: Trees begin as epiphytes on host trees.
[EX A]: trees

[EX Q]: Sentence1: sonar is used to find the location of an object. 
Sentence2: Surface ships use sonar to locate and track submarines.
[EX A]: location

[EX Q]: Sentence1: Communities consist of populations of different species. 
Sentence2: Communities consist of populations of different groups that produce fertile offspring.
[EX A]:
Communities