铁门上的锈迹需要及时清理以防进一步腐蚀。

The ___rust on the iron gate needs to be cleaned to prevent further damage.

玫瑰叶子上出现的红褐色斑点可能是由真菌锈病引起的。

The reddish-brown spots on rose leaves may be caused by fungal ___rusts.

铁门因为没有油漆保护，已经开始生锈了。

The iron gate has started to ___rust because it wasn't painted for protection.