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: high pressure systems cause clear weather. 
Sentence2: Weather Clear weather usually means good visibility.
clear

Sentence1: Human mating behavior also involves some competition. 
Sentence2: Human mating may lead to aggressive behaviors or displays of aggresion.
Human

Sentence1: Smog also contains particulates. 
Sentence2: ozone contains particulates.

contains