a street gang的用法和样例：
- A small time thief-turned-undercover cop teams up with his old criminal partners to infiltrate a street gang involved in a brutal war over territory.
- Cobb and Cornell Jr. both dropped out of school in the tenth grade, joined a street gang and developed gorilla-size heroin habits, which they supported with felonies.
- I am always careful when crossing a street.
- He could never pass a street fight without pitching in.
- A path marked off for pedestrians crossing a street.
- A turf war erupted between street gangs.