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.
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Question: Sentence1: Graphite and diamond are polymorphs of carbon. 
Sentence2: carbon polymorphs are used for making pencil lead.

Answer: carbon


Question: Sentence1: faulting of rock in Earth 's crust causes earthquakes. 
Sentence2: fault movement forms earthquakes.

Answer: earthquakes


Question: Sentence1: Arteries generally carry oxygen-rich blood. 
Sentence2: without oxygen, people can die.

Answer:
oxygen-rich