km

基本解释

Each tower serves an area of approximately 3 sq km.
每个基站的服务范围大概是3平方公里。
Passengers moved from one to another until finally taking a seat on the benches aboard the fastest, which whisked them across the bridge at 16 km/h.
乘客从一条道挪到另一条，直到在最快人行道上的长椅上坐下，这将带领他们以16公里每小时的速度通过大桥。
The underground Italian laboratory, some 120 km (75 miles) to the south of Rome, is the largest of its type in the world for particle physics and cosmic research.
位于格朗萨索的地下实验室，在罗马以南120公里（或75英里），它是世界上此类型最大的粒子物理和宇宙研究实验室。

There's no big city within 200 km, but tourists from all over the world manage to find it.
Then, I tell you I went for 5 km on the second day and another 5 km on the third day.
然后我第二天行进了5公里,第三天又走了5公里
耶鲁公开课 - 基础物理课程节选
You can deal with this by saying not just 5 km, but plus or minus 5 km.
你不能只说5公里,而应该是+5或者-5公里
耶鲁公开课 - 基础物理课程节选

Recently, it had its first sale to install 15 km of pipeline to SQM Inc.
FORBES: Startup Aims To Install Pipelines With Helicopters...Seriously!