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: Most water comes from precipitation. 
Sentence2: aquatic animals require precipitation to survive.

SOLUTION: precipitation

PROBLEM: Sentence1: intense heat has a negative impact on an organism. 
Sentence2: intense heat has a negative impact on plants.

SOLUTION: heat

PROBLEM: Sentence1: keeping food cold is used for keeping food fresh. 
Sentence2: Fresh food is better tasting and better nutritionally, anyway.

SOLUTION:
food