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.

Sentence1: a fire requires oxygen to burn. 
Sentence2: A fire requires something with exactly eight protons to burn.
burn

Sentence1: dew is formed when water vapor condenses over night. 
Sentence2: When water vapor condenses overnight, the temperature has reached the dew point.
condenses

Sentence1: DNA DNA is deoxyribonucleic acid. 
Sentence2: characteristics that are encoded in deoxyribonucleic acid are called genetic traits.

acid