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: Refrigerators are major users of electricity. 
Sentence2: Keeping food fresh for a long period of time requires a lot of electricity.
[A]: electricity


[Q]: Sentence1: Nitrogen is found in proteins, nucleic acids, and chlorophyll. 
Sentence2: Nitrogen, as a gas, is colorless, odorless, and a generally inert element.
[A]: Nitrogen


[Q]: Sentence1: Zooplankton are tiny animals that feed on phytoplankton. 
Sentence2: Zooplankton are tiny animals that feed on diatoms.
[A]:
Zooplankton