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: Mammals generate heat mainly by keeping their metabolic rate high. 
Sentence2: food keeps mammals' metabolic rates high.

Answer: Mammals


Question: Sentence1: Leeches are external parasites. 
Sentence2: Leeches live on the surface of their hosts.

Answer: Leeches


Question: Sentence1: Freezing point depression is a colligative property. 
Sentence2: salts effect the colligative properties of solids.

Answer:
colligative