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: wind is used for producing electricity. 
Sentence2: Winds are caused by pressure differences.
[A]: wind


[Q]: Sentence1: wiring requires an electrical conductor. 
Sentence2: Gold is an excellent conductor of electricity.
[A]: conductor


[Q]: Sentence1: contact between rocks over long periods of time causes rocks to smooth. 
Sentence2: Granite is rock formed by fire.
[A]:
rocks