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: conserving water can be used for survival in a dry environment. 
Sentence2: conserving water can be used for survival in deserts.
[A]: conserving


[Q]: Sentence1: a fire requires oxygen to burn. 
Sentence2: If the oxygen is removed, the fire is smothered.
[A]: oxygen


[Q]: Sentence1: an incandescent light bulb converts electricity into light by sending electricity through a filament. 
Sentence2: light bulbs are powered by heat.
[A]:
bulb