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: a switch is used to start the flow of current in an electrical circuit. 
Sentence2: The flow of electrical current powers a light bulb.
current

Sentence1: DNA is made up of nucleotides. 
Sentence2: Mutations can change the structure of DNA.
DNA

Sentence1: the Earth being tilted on its rotating axis causes seasons. 
Sentence2: Seasonal weather patterns also have a major impact on carrot root diseases.

seasons