设有如下程序： import java.util.*; public class Sun public static void main (String args[ ]) int score; String a; Random r=new Random (); score=r.nextInt (4)+5; switch(score)
case 0: a="E"; break; case 1: a="D"; break; case 2: a="C"; break; case 3: a="B"; break; default: a="A";