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

Answer: plants


Question: Sentence1: a flower 's purpose is to produce seeds. 
Sentence2: Every job has meaning and purpose.

Answer: purpose


Question: Sentence1: a delta is formed by deposition of sediment at the mouth of a river by water fanning out. 
Sentence2: Alluvial deposits can form deltas where the river flows into a lake or ocean.

Answer:
by