若有定义:floatx=1.5;inta=2,b=3,d=5;则正确的switch语句是()
A. switch(a+b){case3:printf("*\n");case2+3:printf("**\n");}
B. switch((int)x);{case1:printf("*\n");case2:printf("**\n");}
C. switch(x);{case1.5:printf("*\n");case2.0:printf("**\n");}
D. switch(a+b){case3:printf("*\n");cased:printf("**\n");}