TASK 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.
PROBLEM: Sentence1: Oil and gasoline are fossil fuels. 
Sentence2: lawn mowers convert fossil fuels into motion.

SOLUTION: fossil

PROBLEM: Sentence1: high pressure systems cause clear weather. 
Sentence2: Weather Clear weather usually means good visibility.

SOLUTION: clear

PROBLEM: Sentence1: a telescope is used for observing stars by astronomers. 
Sentence2: And, of course, the Sun is a star.

SOLUTION:
stars