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: microscope is used to see small things by biologists by making them appear bigger. 
Sentence2: Something invented by Leeuwenhoek is used to see small things by biologists by making them appear bigger.

SOLUTION: appear

PROBLEM: Sentence1: Protein Protein is needed for tissue maintenance and repair. 
Sentence2: protein repairs cells.

SOLUTION: Protein

PROBLEM: Sentence1: Living and surviving are the thing. 
Sentence2: An egg requires warmth to live.

SOLUTION:
Living