The postal system operates a uniform price structure, so it always costs the same to send a letter.邮政系统实行统一的价格结构，所以寄一封信收费总是相同的。The world's oil price structure collapsed with the failure of the major exporters to agree on a new base price.由于主要石油出口国未能就新的基本价格达成协议，世界石油价格体系崩溃了。