道床的英文：
(of railroad transportation) ballast
n. 铁路；铁路公司
v. 迫使；捏造不实之罪使入狱；铺设铁路；在铁路工作；由铁道运输；乘火车旅行
It is veined by railroads.
铁路线四通八达。
They ballasted the railroad.
他们给铁路铺道渣。
They paved the trunk line of a railroad.
他们铺设了铁路的干线。
n. 运输，运送；流放；运输工具
To transport by boat.
用船运输
transportation leakage
运输漏损量
He was sentenced to transportation for life.
他被判处终身流放。
n. 压舱物，压载物；道渣，碎石
v. 给…装压舱物；给…铺道渣
They ballasted the ship.
他们给船只装压舱物。
They ballasted the railroad.
他们给铁路铺道渣。
The ballast placed in the ship can keep the ship steady.
放在船上的压舱物可以保持船的平稳。