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: Fission is a type of reproduction, but a baby is the result of sexual reproduction. 
Sentence2: the fallopian tubes are used to make babies.

Answer: baby


Question: Sentence1: Heat production is increased by shivering and non-shivering thermogenesis . 
Sentence2: Heat production occurs when many muscles contract a little bit all at once.

Answer: Heat


Question: Sentence1: How erosion builds mountains. 
Sentence2: rain can build mountians.

Answer:
builds