程序阅读题:对该程序进行调试,使程序的输出结果为:abc public class Java_1{ public static void main (_____________ [] args ) { char ch ='d'; switch(________) { case 'a': System.out.print ("a");break; case 'b': System.out.print ("b"); case 'c': System.out.print ("c");break; _______________: System.out.print (" abc "); } } }