计算器上有一个特殊的按键，在计算器上显示正整数n时按下这个按键，会等可能的将其替换为0～n﹣1中的任意一个数．如果初始时显示2011，反复按这个按键使得最终显示0，那么这个过程中，9、99、999都出现的概率是（　　）

    Jack and Anna are good friends. They are Chinese. Jack likes sports very much. He can play volleyball , basketball and football . Anna likes music very much . She can't play ball games. But they both like playing on computers . They like eggs , bread and milk for breakfast . For lunch , Anna likes eating vegetables and fruit , but Jack likes chicken and fish . They both like hamburgers .But they don't like ice cream or rice.