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: cold fronts cause thunderstorms as they pass by. 
Sentence2: Cold fronts cause lightning.

A: cold
****
Q: Sentence1: wind is used for producing electricity. 
Sentence2: Winds are caused by pressure differences.

A: wind
****
Q: Sentence1: Most salamanders use their sense of smell to find a mate. 
Sentence2: An amphibian uses its sense of smell to find a mate.

A:
find
****