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.

Input: Consider Input: Sentence1: when a gas in an open container evaporates , that gas spreads out into the air. 
Sentence2: If you place gas in an open box it will evaporate and spread out into the air.

Output: gas


Input: Consider Input: Sentence1: threatening behavior by predators causes a porcupine to extend its quills. 
Sentence2: Fishers are predators that can eat porcupines.

Output: predators


Input: Consider Input: Sentence1: Warm temperatures have helped plant growth and sizing. 
Sentence2: a greenhouse helps  plant growth.


Output: growth