People enjoy talking about "firsts". They like to remember their first love or their first car. But not all firsts are happy ones. One of history's bad but important firsts was the first car accident. Cars were still young when it happened. The accident took place in New York City in May 1896. A man from Massachusetts was visiting the city in his new car. At that time, bicycle riders were still trying to get used to the new set of wheels on the road. No one was sure who was to blame for it. Anyway, the bike and the car hit each other hard. The man on the bike was injured. The driver of the car had to stay in jail and wait for the hospital report on the bicycle rider. Luckily, the rider was not killed. Three years later, another car accident took place. It was again in New York City. A man named Henry Bliss stepped off a streetcar . He was hit by a passing car. Once again, no one was sure just how it happened or whose fault it was. The driver of the car was put in prison. Poor Mr. Bliss became the first person to die in a car accident. The main idea of the passage is   _  .
not all firsts are happy ones two of the first car accidents two unhappy "firsts" bicycle riders get used to cars