给定一篇文章和一个关键词，请返回这个关键词在文章中出现次数的数量。
原文章如下：
"The quick brown fox jumped over the lazy dog. The dog barked, then ran away with the fox. The fox and the dog were never seen again."
关键词：fox
关键词 "fox" 在文章中出现了 2 次。