从词库中随机抽取一个单词，显示一款可帮助学生背英文单词的小软件，在屏幕上时，该单词被随机隐藏了一个、或两个、或三个字母，用户正确填空后，可得分；当得分累积到某些分值时，系统给予鼓励-Randomly selected from the thesaurus in a word, showing a back to help students of English words of small software, on the screen, the words were randomly hide