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: Very often their only metal object in the house is a cooking pot or a knife. 
Sentence2: sharpening a knife causes it to change shape.
[EX A]: knife

[EX Q]: Sentence1: Clouds are one form of condensation. 
Sentence2: Clouds are one form of changing from a gas into a liquid by reducing heat energy.
[EX A]: Clouds

[EX Q]: Sentence1: Population size influences the chances of a species surviving. 
Sentence2: Survival is to live, to live means hope.
[EX A]:
surviving