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: an animal requires air for survival. 
Sentence2: The Moon has no atmosphere and no air.
[A]: air


[Q]: Sentence1: protein is used to repair cells by the human body. 
Sentence2: Meat, fish and chicken are rich sources of protein.
[A]: protein


[Q]: Sentence1: soil is formed by weathering. 
Sentence2: Something described as loamy is formed by weathering.
[A]:
formed