畳の上の水練たたみのうえのすいれん慣用句ことわざknowing the theory but being unable to put it into practicepractising swimming on a tatami mat
百日の説法屁一つひゃくにちのせっぽうへひとつ慣用句ことわざone blunder rendering a long period of effort uselessone fart in a hundred days of sermons