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: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Nitrogen, as a gas, is colorless, odorless, and a generally inert element.

SOLUTION: Nitrogen

PROBLEM: Sentence1: an image in a mirror is formed by reflecting light. 
Sentence2: mirrors can be seen with our eyes.

SOLUTION: mirror

PROBLEM: Sentence1: erosion of soil has a negative impact on the environment. 
Sentence2: Forests provide a clean and comfortable environment.

SOLUTION:
environment