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: All cells share some of the same structures and basic functions. 
Sentence2: Inside the cell is a structure called the nucleus.
[A]: cells


[Q]: Sentence1: Acids dissolve in base and turn blue litmus red. 
Sentence2: acid changes color.
[A]: Acids


[Q]: Sentence1: rest has a positive impact on a health. 
Sentence2: rest is essential to quality of life.
[A]:
rest