当水被加热时，会变成蒸汽。

When water is heated, it turns into ___vapor.

热水壶冒出的蒸汽在寒冷的空气中形成了一片白色的雾气。

The hot kettle released a cloud of white ___vapor into the cold air.

热水的蒸汽很快蒸发到空气中。

The steam from the hot water quickly ___evaporated into the air.