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: Visible and invisible light is energy in the form of electromagnetic waves. 
Sentence2: Eyes are used for seeing animals by sensing electromagnetic waves.

SOLUTION: electromagnetic

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

SOLUTION: expensive

PROBLEM: Sentence1: Bacteria are microorganisms that exist everywhere. 
Sentence2: microorganisms may spread directly from one person to another.

SOLUTION:
microorganisms