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: Interstellar space contains a plasma. 
Sentence2: interstellar space contains electrons, atoms, and stars.
[A]: Interstellar


[Q]: Sentence1: Scientists still know relatively little about Archaea. 
Sentence2: scientists still know relatively little about non-bacterial prokaryotes.
[A]: Scientists


[Q]: Sentence1: Viruses cannot reproduce by themselves. 
Sentence2: rabies cannot reproduce by itself.
[A]:
cannot