在一个寒冷的早晨，热气从滚烫的湖面上升起。

On a cold morning, ___steam rose from the surface of the hot lake.

博物馆里的那台老旧机械是由蒸汽机驱动的。

The old machinery in the museum is powered by a ___steam engine.

我们看着那辆老式的蒸汽火车突突地穿过森林。

We watched the old-fashioned ___steam train chug through the forest.