It never rusts or tarnishes.

它从不生锈，也没有污迹。

Copper nails are better than iron nails because the iron rusts.

铜钉比铁钉好，因为铁钉会生锈。

Iron rusts in ordinary water.

铁在普通的水中会生锈。

Iron rusts in the moist air.

铁在潮湿的空气会生锈。

Iron rusts in the moist air.

铁在潮湿的空气中会生锈。