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.

Sentence1: Aggression is behavior that is intended to cause harm or pain. 
Sentence2: Verbal violence is behavior that is intended to cause harm or pain.
behavior

Sentence1: skin is used for protecting the body from harmful substances. 
Sentence2: Acids are harmful to tissue.
harmful

Sentence1: An electric circuit is a closed path for electron flow. 
Sentence2: Powering an electrical device with a battery requires electron flow.

electron