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: Coal-fired power stations can cause acid rain and contribute to global warming. 
Sentence2: Certain types of electricity production can cause acid rain and contribute to global warming.

rain