功能描述
单词相关主要功能：
1. 分类：丰富任选
2. 测验：两万多单词，百级通关
3. 听词：可锁屏听单词、释义和例句
4. 词课：听、说、写、译练习
5. 复习：错题、生词、例句
6. 其它：用户词汇量统计，真人美音、英音、男声、女声，双语界面任选
汉字相关主要功能：与单词类似
Vocabulary-related main features:
1. Category: plenty at your fingertips
2. Quiz: over 20,000 words in 100 levels
3. Audible: listen to words, definitions and example sentences even with locked screen
4. Lesson: listening, speaking, writing and translation drills
5. Review: wrong answers, new words, example sentences
6. The rest: vocabulary counter，human pronunciation in US or UK accent and male or female voice, and optional bilingual layout
Character-related main features: similar to those of vocabulary