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: Veins generally carry deoxygenated blood. 
Sentence2: Blood carries blood cells.

SOLUTION: blood

PROBLEM: Sentence1: Herbs are medicines and aids. 
Sentence2: herbs are used for curing people when they are sick.

SOLUTION: Herbs

PROBLEM: Sentence1: Playing is one way mammals and other animals learn how to behave. 
Sentence2: Playing is one way mammals and other animals learn how to be assertive.

SOLUTION:
Playing