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.

Sentence1: Oil and gasoline are fossil fuels. 
Sentence2: lawn mowers convert fossil fuels into motion.
fossil

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.
a

Sentence1: Amphibians have a relatively complex circulatory system with a three-chambered heart. 
Sentence2: Salamanders have a relatively complex circulatory system with a three-chambered heart.

circulatory