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: Cows are social animals. 
Sentence2: when a cow moves, chemical energy is converted to mechanical energy.

SOLUTION: Cows

PROBLEM: Sentence1: Fractures heal when osteoclasts form new bone. 
Sentence2: Fractures A fracture is a broken or cracked bone.

SOLUTION: Fractures

PROBLEM: Sentence1: Roundworms Nearly all puppies and kittens have roundworms. 
Sentence2: Puppies and kittens may have parasitic worms.

SOLUTION:
kittens