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: the emission of sulfur dioxide causes acid rain. 
Sentence2: Sulfur dioxide emissions causes soil nutrients to be leached away.

Answer: dioxide


Question: Sentence1: Osteoporosis is a disease characterized by a decrease in bone mineral density. 
Sentence2: a disease in which osteoclasts are more active than osteoblasts results in a decrease in bone mineral density.

Answer: bone


Question: Sentence1: hunting requires seeing prey. 
Sentence2: Hunting allows for predators to attack, then kill and eat.

Answer:
hunting