单词处理，根据读入的文件，统计文件中纯英文字母组成的单词，并统计该单词出现的次数，并且输出到指定文件中，每行显示一个单词和出现次数，并用“，”隔开-Word processing, according to read the files, Statistics file letter words in plain English, and statistics the number of occurrences of the word, and the output to the specifi