kilometer是可数名词。例句：Thats a cubic kilometer. 那就是一千立方米。Its half a kilometer away from here. 离这儿半公里远。
Whats the area of Canada in square kilometer? 加拿大的面积有多少平方公里？She watched the train drag her car almost a kilometer down the railway tracks. 她看着火车把她的车沿着铁轨拖了将近一公里。