distance between lines

例句：

1. 1. The two countries are separated by a vast distance.
   这两个国家相隔甚远。
2. 2.The train travels at a constant speed without any distance between stations.
   火车以恒定速度行驶，没有车站之间的间隔。
3. 3. The distance between the two cities is about 500 kilometers.
   两座城市之间的距离大约是500公里。