galvanized mild steel roofing bolt and nut

例句：

1. 1. The roofis made of galvanized mild steel.
   屋顶是用镀锌轻钢制成的。
2. 2. They usedto use galvanized iron for fences.
   他们过去用镀锌铁做篱笆。
3. 3. Galvanized steel is more durablethan uncoated steel.
   镀锌钢比未涂层钢更耐用。