单项选择题
若有定义:float x=1.5;int a=1,b=3,c=2;则正确的switch语句是()。
A.switch ( {case 1.0: printf("*\n"); case 2.0: printf("**\n");}
B.switch ( (in; {case 1: printf("*\n"); case2: printf("**\n");}
C.switch (a+ {case 1:printf("*\n"); case 2+1: printf("**\n");}
D.switch (a+) {case 1: pfintf("*\n")}; case c: printf("**\n"));}