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: a circle graph can be used to display percents. 
Sentence2: pie charts are circle graphs.
[A]: circle


[Q]: Sentence1: chemical splashing can cause harm to humans. 
Sentence2: chemical splashing can cause harm to animals.
[A]: cause


[Q]: Sentence1: Rust stains are the result of oxidation. 
Sentence2: metal becomes orange on the surface as a  result of oxidation.
[A]:
oxidation