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 is used to produce electricity by burning in coal-fire power stations. 
Sentence2: Coal produces electricity by being heated up in coal-fire power stations.

electricity