根据成绩输出他的评分成绩（A-F）：

A：90~100

B：80-89

C：70~79

D：60~69

F：<60

def num(x):
        if (x>=90 and x<=100):
                print ‘A’
        elif (x>=80 and x<=89):
                print ‘B’
        elif (x>=70 and x<=79):
                print ‘C’
        elif (x>=60 and x<=69):
                print ‘D’
        elif (x>=0 and x<60):
                print ‘F’

调用函数num就可以了。