forge pig iron

例句：

1. 1. The blacksmith forged a new sword from the old one.
   铁匠从旧剑中锻造出一把新剑。
2. 2. He smelted iron in his workshop.
   他在工作室里熔炼铁。
3. 3. The forge glowed with heat as the metal was heated.
   随着金属被加热，火炉发出炽热的光芒。