yT, add <NO> Tag functionality

Explanation how works the application : This application removes letters in several words to help user memorize texts. In order to help learning lessons, the program displays any text file sentence per sentence, and only shows start letters for a few words. The user must type remaining letters. According to the level selected by the user the number of words asked and the number of hint letters change. Explanation of the task : When <NO> Tag is added before a word in edit mode, the word in question can't be asked to the user. For example: Hello the world. could become He___ the wo__. but Hello the <NO>world. would become, at the same level: He__ the world. But, if the number of words asked before to put this tag is for exemple 3, then the number of words asked after must be the same. I communicate only via freelancer and I pay only after have tested the job.