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: Competition may lead to aggressive behaviors or displays of aggression. 
Sentence2: Aggression Aggression and violence often go together.
[A]: aggression


[Q]: Sentence1: a flashlight converts chemical energy into light energy. 
Sentence2: Only as long as there are batteries in the flashlight, the flashlight will function.
[A]: flashlight


[Q]: Sentence1: Cotton and shredded tissue paper make excellent nesting materials. 
Sentence2: Cotton and shredded tissue paper are used for protecting young by birds.
[A]:
Cotton