Keep up your English, or it will get rusty.
Knives get rusty when not sharpened.
If the machinery were not maintained properly, It would get rusty as time passes.
FRP light pole,in its service life,will not get rusty,not easy to be scrapped and no need to be weather-resistance is bettor than that of wood,aluminum,steel and cement ones.
Left in the rain [/i], the metal will soon get rusty.