a crosstown bus的用法和样例：
- Also, we'd like some transfers for the Thirty-fourth Street crosstown bus.
- I think people try to make such a big deal out of (the two teams) being a rivalry when it's really a crosstown thing.
- As I was waiting for a bus a brick fell on my head.
- Can I get a ticket for the sight-seeing bus here?
- A new bus line has been brought into service.