判断学生成绩等级
a = int(input("请输入你的成绩:
"))
if 90 <= a <= 100:
print("你的成绩等级:A")
elif 80 <= a < 90:
print("你的成绩等级:B")
elif 70 <= a < 80:
print("你的成绩等级:C")
elif 60 <= a < 70:
print("你的成绩等级:D")
elif 0 <= a < 60:
print("你的成绩等级:E")
a = int(input("请输入你的成绩:
"))
if 90 <= a <= 100:
print("你的成绩等级:A")
elif 80 <= a < 90:
print("你的成绩等级:B")
elif 70 <= a < 80:
print("你的成绩等级:C")
elif 60 <= a < 70:
print("你的成绩等级:D")
elif 0 <= a < 60:
print("你的成绩等级:E")