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.

[Q]: Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: PALight Flashlights are the ultimate personal LED flashlights.
[A]: flashlight


[Q]: Sentence1: Many birds perform elaborate courtship dances. 
Sentence2: Many birds perform dances before they mate.
[A]: Many


[Q]: Sentence1: Olfaction is the sense of smell. 
Sentence2: olfaction is used for finding food by some animals.
[A]:
Olfaction