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: if an object is made of a material then that object has the properties of that material. 
Sentence2: An object is an item in the real world.

SOLUTION: object

PROBLEM: Sentence1: Bees feed on nectar and pollen. 
Sentence2: Plant reproduction often requires bees and nectar.

SOLUTION: Bees

PROBLEM: Sentence1: Amphibians are the first true tetrapods, or vertebrates with four limbs. 
Sentence2: Amphibians with four limbs are more advanced than fish.

SOLUTION:
Amphibians