怎么理解下面这个英语句子?

问题描述:

怎么理解下面这个英语句子?
reduce the costs for trade negotiations on and transactions of agricultural products
这个句子怎么理解?为什么要加on?

= reduce the costs for trade negotiations on agricultural products and transactions of agricultural products 是属于两个介词共享agricultural products,因为negotiations on ...和transactions of ...的固定...