若定义float x;int a,b,则正确的switch语句是:
A.
switch(x) { case 1.0:printf("*\n"); case 2.0:printf("**\n"); }
B.
switch(x) { case 1.2:printf("*\n"); case 3:printf("**\n"); }
C.
switch(a+b) { case 1:printf"*\n"}; case 1+2:printf("**\n") }
D.
switch(a+b) { case 1:printf("*\n"); case 2:printf("**\n"); }