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: skin is used for protecting the body from harmful substances. 
Sentence2: Acids are harmful to tissue.

Answer: harmful


Question: Sentence1: Flowers produce spores that develop into gametophytes. 
Sentence2: Flowers produce spores that develop into seed plants.

Answer:
Flowers