Use "subway system" in a sentence

1. The first in 1995; when the doomsday cult Aum Shinrikyo released sarin gas in the Tokyo subway system! Luckily only 13 died for the sarin gas was not pure enough

2. , but I didn't see how their whole subway system could be less than twelve years old

3. Pre-Summer Olympics Athens had no modern airport, poor transportation infrastructure with a very basic and limited subway system