在给定的字符串中查找指定单词的出现次数。
字符串："Natural language processing is a subfield of linguistics, computer science, and artificial intelligence concerned with the interactions between computers and human language, in particular how to program computers to process and analyze large amounts of natural language data."
指定单词： "language"
指定单词“language”在给定的字符串中出现了2次。