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: Angiosperm sporophyte is dominant. 
Sentence2: Flowers form on angiosperms.

Answer: Angiosperm


Question: Sentence1: Shade trees can be deciduous. 
Sentence2: Some shade trees can shed their leaves.

Answer:
Shade