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: a switch is used to start the flow of current in an electrical circuit. 
Sentence2: lights are on when there is flow of current in an electrical circuit.
[EX A]: circuit

[EX Q]: Sentence1: Mad Cow disease is a concern. 
Sentence2: pathogens can cause Mad Cow.
[EX A]: Cow

[EX Q]: Sentence1: Playing is just one of many ways that mammals and other animals learn how to behave. 
Sentence2: Children learn through play and in other ways.
[EX A]:
Playing