This is the 4321st most frequent Chinese word.
巴士
Bus.
In this sentence, '巴士' is used to refer to the means of transportation—a bus.
我每天早上都乘坐巴士去上班。
I take the bus to work every morning.
Here, '巴士' is used to describe the public transportation system.
城市里的巴士线路非常便捷。
Bus routes in the city are very convenient.
In this case, '巴士' represents a specific scheduled bus.