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.

[EX Q]: Sentence1: propulsion is used for flying by a spacecraft. 
Sentence2: Jets are used for flying by spacecraft.
[EX A]: flying

[EX Q]: Sentence1: Translation reads the genetic code in mRNA and makes a protein. 
Sentence2: Nucleotide sequences are read in mRNA and a protein is made.
[EX A]: mRNA

[EX Q]: Sentence1: gases released during the use of fossil fuels causes global warming. 
Sentence2: Cars and factories burn fossil fuels, releasing nitrogen oxide gases and reactive organic compounds.
[EX A]:
fossil