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.

[EX Q]: Sentence1: Propane can be either a liquid or a gas. 
Sentence2: heat can be added to propane to change it's properties through the boiling process.
[EX A]: Propane

[EX Q]: Sentence1: drought is when amount of precipitation decreases. 
Sentence2: Drought decreases the availability and abundance of the natural food supply.
[EX A]: drought

[EX Q]: Sentence1: Scales protect fish from predators and parasites and reduce friction with the water. 
Sentence2: Scales provide protection and camouflage.
[EX A]:
protect