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: Propane can be either a liquid or a gas. 
Sentence2: heat can be added to propane to change it's properties through the boiling process.

Answer: Propane


Question: Sentence1: Shivering occurs when many muscles contract a little bit all at once. 
Sentence2: Honey bees can shiver.

Answer:
Shivering