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: All frogs are amphibians. 
Sentence2: frogs have permeable skin that easily absorbs substances from the environment.

Answer: frogs


Question: Sentence1: Most copepods feed on phytoplankton. 
Sentence2: most copepods feed on bacteria and algae that use sunlight to make food.

Answer: copepods


Question: Sentence1: Fertilization is the penetration of the egg by a sperm. 
Sentence2: The penetration of the egg by a sperm takes place inside the female organism.

Answer:
egg