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.

Q: 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.

A: object
****
Q: Sentence1: erosion of soil has a negative impact on the environment. 
Sentence2: erosion of soil has a negative impact on forests.

A: erosion
****
Q: Sentence1: Feathers help birds fly and provide insulation. 
Sentence2: Feathers help animals in the class Aves fly and give them insulation.

A:
Feathers
****