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.

Ex Input:
Sentence1: Earthquakes are natural disasters. 
Sentence2: earthquakes can cause animals to leave an environment.

Ex Output:
Earthquakes


Ex Input:
Sentence1: the ovaries are used in reproduction. 
Sentence2: Unlike most female animals, which have two functioning ovaries, the chicken usually has only one.

Ex Output:
ovaries


Ex Input:
Sentence1: thirst is used to make an animal realize that it needs to replenish its bodily water by the body. 
Sentence2: Drinking non-carbonated beverages will replenish fluids.

Ex Output:

replenish