11.   In Tehran, electric buses came to a halt and passengers were stranded when the single underground subway line also lot power.

12.   In Tehran, electric buses came to a halt, and passengers were stranded when the single underground subway line also lost power.

13.   Sarin, a nerve gas developed by the Nazis in World War II, is heavier than air, so it is difficult to remove from underground subway tunnels.

14.   Then, with the advent of gasoline-powered buses and underground subways, most cities gradually dropped trolleys.

15.   Then, with the advent of gasoline-powered buses and underground subways, most North American cities gradually dropped trolleys.

16.   This was the first case in the world in which a quake has destroyed underground subway posts in a major city, an official told the Kyodo News Service.

17.   Rescuers worked throughout the night and believed they had freed all those who were trapped in an underground subway tunnel after the collision.