统计一篇文档中每个单词出现的次数，频率

i i i i love you dear i love her too! i i i wish to wish the wish you wish to wish but if you wish the wish the witch wishes i won't wish the wish you wish to wish if you understand, say understand,if you don't understand say don't understand,but if you understand and say don't understand,how do i know that you understand.