A、 switch(x){case 1.0: printf(" * \n");
Case 2.0: printf("** \n");}
B、 switch( ( int)x) ;{case 1: printf(" * \n");
Case 2: printf("**\n");}
C、 switch(a +b){case 1: printf(" *\n");
Case2 +1: printf("**\n");}
D、 switch(a +b){case 1: printf(" *\n");
Case c: printf(" **\n");}