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: Autumn brings the changing of the seasons. 
Sentence2: Earth 's tilt on its rotating axis causes autumn.

Answer: Autumn


Question: Sentence1: Without light there is no sense of vision. 
Sentence2: Glass causes a sense of vision.

Answer: sense


Question: Sentence1: Birds are a class of the chordates or vertebrate phylum. 
Sentence2: birds have a backbone.

Answer:
Birds