switch语句改写成if语句答:include <stdio.h> include"stdio.h"void main(){ float a,b,s;char c;printf("Please input expession:a+(-,*,/)b\n");scanf("%f%c%f",&a,&c,&b);if(c=='+') printf("%f\n",a+b);else if(c=='-') printf("%f\n",a-b);else if(c=='*') printf("%f\n",a...