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: Fertilization occurs naturally in the fallopian tubes. 
Sentence2: fertilization is used for reproduction.

Answer: Fertilization


Question: Sentence1: Muscles can only contract. 
Sentence2: Contraction is a type of movement.

Answer: contract


Question: Sentence1: an electric stove transforms electrical energy to heat energy. 
Sentence2: electric motors and stoves transform electricity.

Answer:
stove