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: if a neutral atom loses an electron then an atom with a negative charge will be formed. 
Sentence2: Ice crystals that are formed have a negative charge.

Answer: charge


Question: Sentence1: Faster metabolism means more calories consumed, and usually, weight loss. 
Sentence2: mammals generate heat by consuming calories.

Answer: calories


Question: Sentence1: Mammalian teeth are important for digestion. 
Sentence2: bats' teeth are important for digestion.

Answer:
digestion