preexistent的翻译，读音

例句

The core idea of the method was to seek frequently-used sets of services combination sequences from the preexistent ones, then used the frequent sequences to recommend the services. 其核心思想是通过从以往服务组合序列中发现高频率出现的组合序列集，然后利用该序列集进行服务推荐。

The preexistent experiences from other large countries with a great diversity of aquatic ecosystem are beneficial to the nationwide forthcoming watershed restoration and management in China. 国际河流分类体系的研究成果对于我国多类型河流的生态恢复与管理具有重要的借鉴意义。