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: evaporation can be used for separating a solute from a solvent in a solution. 
Sentence2: Evaporation can be used for segregation a solute from a solvent in a solution.

Answer: a


Question: Sentence1: Speciation events are thus examples of macroevolution. 
Sentence2: Speciation events occur over geologic time above the level of the species.

Answer: Speciation


Question: Sentence1: skin is used for breathing air by frogs. 
Sentence2: Frogs breathe and absorb water through their skin, which is periodically shed.

Answer:
breathing