5.2a Do you know them? 12 a Goods-producing companies 9 3 belong to the secondary sector 765 a service-producing firms to the tertiary, etc a The companies listed have been selected to fit into these two main categories5.2 A Do you know them? ◼ Goods-producing companies belong to the secondary sector. ◼ service-producing firms to the tertiary, etc. ◼ The companies listed have been selected to fit into these two main categories