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: All gravitational forces are attractive, there is no repulsive gravitational force. 
Sentence2: the mass of an object causes the attractive force exerted by that object.

forces