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 usually requires a warm body temperature for survival. 
Sentence2: Warm blooded animals have a constant body temperature.
[EX A]: animal

[EX Q]: Sentence1: All cells share some of the same structures and basic functions. 
Sentence2: Inside the cell is a structure called the nucleus.
[EX A]: cells

[EX Q]: Sentence1: Though most trout are freshwater fish, some live in marine waters. 
Sentence2: some mollusks live near trout.
[EX A]:
trout