iron是可数名词吗

A boy came towards them, rolling an iron hoop.

一个男孩滚着一个铁环朝他们走来。

Iron reacts with water and air to produce rust.

铁和水及空气发生反应产生铁锈。

I'll need to iron that dress before I can wear it.

我得先把那件连衣裙烫平再穿。