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: the emission of sulfur dioxide causes acid rain. 
Sentence2: Sulfur dioxide emissions causes soil nutrients to be leached away.

SOLUTION: dioxide

PROBLEM: Sentence1: Mutations are essential for evolution to occur. 
Sentence2: Genes are altered for evolution to occur.

SOLUTION: evolution

PROBLEM: Sentence1: Organic molecules are the basic building blocks of living organisms on earth. 
Sentence2: cells are the microscopic parts of  organic molecules of living organisms.

SOLUTION:
Organic