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: lightning can cause a forest fire. 
Sentence2: Lightning can cause a natural cycle in forests.
[EX A]: lightning

[EX Q]: Sentence1: Heat and temperature are the same. 
Sentence2: a thermometer is used to measure heat.
[EX A]: Heat

[EX Q]: Sentence1: Light is electromagnetic radiation. 
Sentence2: A bulb requires electrical energy to produce electromagnetic radiation.
[EX A]:
electromagnetic