iron是可數名詞嗎

A boy came towards them, rolling an iron hoop.

一個男孩滾着一個鐵環朝他們走來。

Iron reacts with water and air to produce rust.

鐵和水及空氣發生反應產生鐵鏽。

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

我得先把那件連衣裙燙平再穿。