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: Cells are the microscopic building blocks of organisms. 
Sentence2: proteins are the building blocks of organisms.

SOLUTION: organisms

PROBLEM: Sentence1: Telephone Telephone calls are expensive. 
Sentence2: Communicating by transmitting sound is expensive.

SOLUTION: expensive

PROBLEM: Sentence1: Most carcinogens cause cancer by producing mutations in DNA. 
Sentence2: Asbestos causes cancer.

SOLUTION:
cancer