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: the uterus is used in reproduction. 
Sentence2: Reproduction uses the same organ as menstruation.

Answer: reproduction


Question: Sentence1: Sperm had to swim from male to female reproductive organs for fertilization. 
Sentence2: If fertilized, the egg implants itself in the uterus.

Answer: fertilization


Question: Sentence1: beads of water are formed by water vapor condensing. 
Sentence2: beads of h2o are formed by h2o vapor condensing.

Answer:
beads