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 switch is used to start the flow of current in an electrical circuit. 
Sentence2: The flow of electrical current powers a light bulb.

Answer: current


Question: Sentence1: Warm temperatures have helped plant growth and sizing. 
Sentence2: a greenhouse helps  plant growth.

Answer: growth


Question: Sentence1: Humans have collected and grown mushrooms for food for thousands of years. 
Sentence2: Humans have collected and grown fungi for food for thousands of years.

Answer:
Humans