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: nectar is used for attracting pollinators by plants. 
Sentence2: butterflies pollinate plants.

Answer: plants


Question: Sentence1: Light and darkness are both essential for plant growth. 
Sentence2: plants need darkness to grow.

Answer:
growth