6级单词背诵系统，可以实现单词初记，复习，以及测试功能，将单词分为三种类别，完全认识的，不完全认识的，完全不认识的，方便记忆-6 word recitation system that can realize the beginning of a word in mind that review, as well as testing functions, will be divided into three categories of words, fully aware of which d