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.

Q: Sentence1: Bees feed on nectar and pollen. 
Sentence2: Plant reproduction often requires bees and nectar.

A: Bees
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Q: Sentence1: Enveloped viruses make their own membranes. 
Sentence2: Some viruses make their own membranes.

A: make
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Q: Sentence1: Animals behave in a variety of ways which enhance their chances of survival and reproduction. 
Sentence2: Animals with better senses have a positive chance of reproduction.

A:
Animals
****