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: Enveloped viruses make their own membranes. 
Sentence2: Some viruses make their own membranes.

A: make
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Q: Sentence1: Polyps usually reproduce asexually. 
Sentence2: Polyps usually reproduce several different ways.

A: Polyps
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Q: Sentence1: Puberty is the period during which humans become sexually mature. 
Sentence2: Breasts develop during puberty .

A:
Puberty
****