一：鞋子生命周期

一款新鞋子需要大量的广告来宣传，大量的产品进入市场后开始慢慢成熟，收到人们青睐。随着时间推移，产品开始过时，需求下降。

图片发自简书App

二：Product live cycle

主旨：The product cycle is an economic theory that was developed by Raymond Vernon in response to the failure of the Heckscher-Ohlin model to explain the observed pattern of international trade.

关键单词：economic、international trade、applies、comparative

https://en.m.wikipedia.org/wiki/Product_life-cycle_theory