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.

Example Input: Sentence1: the emission of sulfur dioxide causes acid rain. 
Sentence2: Sulfur dioxide emissions causes soil nutrients to be leached away.
Example Output: dioxide

Example Input: Sentence1: disease-causing microbes have a negative impact on the body. 
Sentence2: pathogens have a negative impact on the body.
Example Output: body

Example Input: Sentence1: Fungi spores can develop into new haploid individuals without being fertilized. 
Sentence2: Spores of Candida and Aspergillus can develop into new haploid individuals without being fertilized.
Example Output:
being