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: keeping food cold is used for keeping food fresh. 
Sentence2: Keeping food at 40 degrees F or lower is used for keeping food fresh.
[A]: food


[Q]: Sentence1: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Life without protein is impossible.
[A]: proteins


[Q]: Sentence1: zinc has a positive impact on the healing of wounds. 
Sentence2: zinc has a positive impact on the healing of cuts.
[A]:
has