Definition: 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: Sentence1: ice wedging is when ice causes rocks to crack by expanding in openings. 
Sentence2: Water causes rocks to crack by turning to ice in its openings.

crack