The new ships, propelled by gas turbines, require less maintenance than older, steam-driven ones.这些由汽轮机驱动的新型轮船比蒸汽驱动的老式轮船更易于养护。The engines are driven by steam.这些发动机是由蒸汽驱动的。The train is propelled by steam.这列火车是由蒸汽驱动的。The engine is driven by steam.这台发动机由蒸汽驱动。