Title: Railway electrification system.
Question: How did it become possible to share the voltage for different types of train?

Title: Genome.
Question: What aspect of a genome can genome compositions help researchers in learning about?

Title: Copyright infringement.
Question: What is it called when a law disallows copyright owners from denying a license for certain uses?

Title: Seattle.
Question:
What genre of music are Nirvana and Soundgarden?