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: friction is used for stopping a vehicle by brakes. 
Sentence2: friction is used for stopping a car by brakes.
brakes

Sentence1: pathogens can cause disease. 
Sentence2: pathogens affects the immune system.
pathogens

Sentence1: Bees are naturalized on every continent except Antarctica. 
Sentence2: Honey bees produce honey.

Bees