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: Producers make food from inorganic molecules. 
Sentence2: Decomposition is the breakdown of organic molecules into inorganic molecules.

SOLUTION: inorganic

PROBLEM: Sentence1: An accounting period is simply a period of time. 
Sentence2: seconds are used to measure a period.

SOLUTION: period

PROBLEM: Sentence1: Iron rusts in the presence of oxygen and water. 
Sentence2: oxygen and water will cause metal to turn orange.

SOLUTION:
oxygen