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: Babies that are very large or very small at birth are less likely to survive. 
Sentence2: Poor nutrition while in the womb is the major reason why babies are small at birth.

Answer: birth


Question: Sentence1: weathering means breaking down rocks from larger whole into smaller pieces by weather. 
Sentence2: Trash collectors work in all types of weather, including rain and snow.

Answer: weather


Question: Sentence1: if an animal lives under ground then that animal will be protected from a wild fire. 
Sentence2: Some animals, like moles and earthworms spend their entire lives underground.

Answer:
ground