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: if a thermal conductor is exposed to a source of heat then that conductor may become hot. 
Sentence2: if a thermal conductor is exposed to the sun then that conductor may become hot.

is