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: a flashlight converts chemical energy into light energy. 
Sentence2: Chemical energy converted to light energy requires batteries.

Answer: chemical


Question: Sentence1: Mollusks are invertebrates such as the common snail. 
Sentence2: snails have no backbone.

Answer: snail


Question: Sentence1: Hurricanes are categorized by the Saffir-Simpson Scale. 
Sentence2: Something categorized by the Saffir-Simpson scale converts heat energy into mechanical energy.

Answer:
Saffir-Simpson