单选题：在课本【例2-4】中，如果要增加一个出错处理机制，当输入的用水量x小于0时，打印提示语句"输入数据有误"，下列哪个程序段可以正确

在课本【例2-4】中，如果要增加一个出错处理机制，当输入的用水量x小于0时，打印提示语句"输入数据有误"，下列哪个程序段可以正确地使用else-if语句实现该功能？ @[D](2)

A.
```
if(x<=0)
printf("输入数据有误\n");
else if(x<=15)
{y=4*x/3; printf("y=f(%f)=%.2f\n",x,y);}
else
{y=0.25*x-10.5; printf("y=f(%f)=%.2f\n",x,y);}
```
B.
```
if(x<0)
printf("输入数据有误\n");
else if(0<=x<=15)
{y=4*x/3; printf("y=f(%f)=%.2f\n",x,y);}
else
{y=0.25*x-10.5; printf("y=f(%f)=%.2f\n",x,y);}
```
C.
```
if(x<0)
printf("输入数据有误\n");
else if(x<=15)
{y=4*x/3;}
else
{y=0.25*x-10.5;}
printf("y=f(%f)=%.2f\n",x,y);
```
D.
```
if(x<0)
printf("输入数据有误\n");
else if(x<=15)
{y=4*x/3; printf("y=f(%f)=%.2f\n",x,y);}
else
{y=0.25*x-10.5; printf("y=f(%f)=%.2f\n",x,y);}
```




A.
```
if(x<=0)
printf("输入数据有误\n");
else if(x<=15)
{y=4*x/3; printf("y=f(%f)=%.2f\n",x,y);}
else
{y=0.25*x-10.5; printf("y=f(%f)=%.2f\n",x,y);}
```
B.
```
if(x<0)
printf("输入数据有误\n");
else if(0<=x<=15)
{y=4*x/3; printf("y=f(%f)=%.2f\n",x,y);}
else
{y=0.25*x-10.5; printf("y=f(%f)=%.2f\n",x,y);}
```
C.
```
if(x<0)
printf("输入数据有误\n");
else if(x<=15)
{y=4*x/3;}
else
{y=0.25*x-10.5;}
printf("y=f(%f)=%.2f\n",x,y);
```
D.
```
if(x<0)
printf("输入数据有误\n");
else if(x<=15)
{y=4*x/3; printf("y=f(%f)=%.2f\n",x,y);}
else
{y=0.25*x-10.5; printf("y=f(%f)=%.2f\n",x,y);}
```


答案：D