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: measuring the hardness of minerals requires scratching those materials. 
Sentence2: To figure out the hardness of a mineral, the Moh's scale of hardness is used.
[A]: minerals


[Q]: Sentence1: protein is used to repair cells by the human body. 
Sentence2: Wound healing requires protein.
[A]: protein


[Q]: Sentence1: Water is made up of H2O molecules. 
Sentence2: cycles of freezing and thawing h2o causes ice wedging.
[A]:
H2O