求大佬帮我看看这个到底哪里出错，怎么改

#include <stdio.h>
void main()
{
int mark;
float score;
char grade;
do{
printf(“please input the score<0-100>:”);
scanf("%f", &score);

if (score <= 100)
{
	mark = (int) (score/10);
	switch (mark)
	{
		case 10:
		case 9:
			grade = 'A';
			printf("score=%.1f,grade=%c\n", score, grade);
			break;
		case 8:
			grade ='B';
			printf("score=%.1f,grade=%c\n", score, grade);
			break;
		case 7:
			grade = 'C';
			printf("score=%.1f,grade=%c\n", score, grade);
			break;
		case 6:
			grade = 'D';
			printf("score=%.1f,grade=%c\n", score, grade);
			break;
		case 5:
		case 4:
		case 3:
		case 2:
		case 1:
		case 0:
			grade = 'E';
			printf("score=%.1f,grade=%c\n", score, grade);
			break;
}
}
else
	printf("\n");
}while (score < 0 || score > 100);

return 0;
}`