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: Veins generally carry deoxygenated blood. 
Sentence2: Blood carries blood cells.

A: blood
****
Q: Sentence1: Estuaries display characteristics of both marine and freshwater biomes. 
Sentence2: freshwater environments have little salt.

A:
freshwater
****