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: Mitosis is cell division. 
Sentence2: mitosis often causes growth.

SOLUTION: Mitosis

PROBLEM: Sentence1: chemical splashing can cause harm to humans. 
Sentence2: chemical splashing can cause harm to animals.

SOLUTION: cause

PROBLEM: Sentence1: Pneumonia may be caused by an infection or injury of the lungs. 
Sentence2: Legionnaires' disease is a type of pneumonia.

SOLUTION:
Pneumonia