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.

[Q]: Sentence1: when electricity flows to a light bulb , the light bulb will turn on. 
Sentence2: water pumps can turn on light bulbs.
[A]: bulb


[Q]: Sentence1: an animal requires nutrients to grow and heal. 
Sentence2: Microbes can help an animal to grow and heal.
[A]: grow


[Q]: Sentence1: Air pollution harms the respiratory and circulatory systems. 
Sentence2: Breathing pollutants can harm the respiratory system.
[A]:
respiratory