python 字典如何输出键和值，百分制转换为等级制

Question

def change(i):

    for i in score.values():
        if i >= 90 :
            result = 'A'
        elif i>=80:
            result = 'B'
        elif i >= 70:
            result = 'C'
        elif i >= 60:
            result = 'D'
        else:
            result = 'E'
    return result


score = {'李明':80,'张壮壮':95,'王娟':77,'赵帅':65,'朱煜':43}
for k in score.keys():
    x = score[k]
    result = change(x)
    print ('{}的等级为：{}'.format(k,result))

格式：
李明的等级为：B
张壮壮的等级为：A
王娟的等级为：C
赵帅的等级为：D
朱煜的等级为：E

现在问题是字典的键和值对应不起来，所有人的等级都显示为E。

Answer 1

def change(i):
    if i >= 90 :
        return 'A'
    elif i>=80:
        return 'B'
    elif i >= 70:
        return 'C'
    elif i >= 60:
        return 'D'
    else:
        return 'E'
score = {'李明':80,'张壮壮':95,'王娟':77,'赵帅':65,'朱煜':43}
for k in score.keys():
    x = score[k]
    result = change(x)
    print ('{}的等级为：{}'.format(k,result))