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: keeping food cold is used for keeping food fresh. 
Sentence2: Keeping food at 40 degrees F or lower is used for keeping food fresh.

SOLUTION: food

PROBLEM: Sentence1: sonar is used to find the location of an object. 
Sentence2: Surface ships use sonar to locate and track submarines.

SOLUTION: location

PROBLEM: Sentence1: Genes live on chromosomes, chromosomes live in cells. 
Sentence2: DNA found in cells.

SOLUTION:
cells