#include<stdio.h>
void main()
{
??? int i = 99;
??? int grade;

??? if (i>=90)
??? {
??????? grade = 'A';
??? }
??? else if (i>=70)
??? {
??????? grade = 'B';
??? }
??? else if (i>=60);
??? {
??????? grade = 'C';
??? }
??? else
??? {
??????? grade = 'D';
??? }
??? printf("%c",grade);
}

?

error：'else' without a previous 'if'