偶然发现Costco在牛津高阶词典的美式发音好像是把末尾的kəʊ发成了kaʊ。查询官网也是如此：
Costco - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner’s Dictionary at OxfordLearnersDictionaries.com
网络搜索了一下，没有发成kaʊ的