km

基本解释

Each tower serves an area of approximately 3 sq km.
每個基站的服務範圍大概是3平方公裡。
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.
乘客從一條道挪到另一條，直到在最快人行道上的長椅上坐下，這將帶領他們以16公裡每小時的速度通過大橋。
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.
位於格朗薩索的地下實騐室，在羅馬以南120公裡（或75英裡），它是世界上此類型最大的粒子物理和宇宙研究實騐室。

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.
然後我第二天行進了5公裡,第三天又走了5公裡
耶魯公開課 - 基礎物理課程節選
You can deal with this by saying not just 5 km, but plus or minus 5 km.
你不能衹說5公裡,而應該是+5或者-5公裡
耶魯公開課 - 基礎物理課程節選

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