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: harming an animal species causes that animal 's population to decrease. 
Sentence2: Oil spill sare harmful to animals and the enviroment.
harming

Sentence1: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Lawns eat nitrogen.
Nitrogen

Sentence1: Mold allergenicity Molds are strong allergens . 
Sentence2: molds are antigens.

Mold