if 分支
score = int(input("你的数学成绩为:"))
if 90 <= score <= 100:
print("优秀")
elif 80 <= score < 90:
print("良好")
elif 60 <= score < 80:
print("及格")
else:
print("不及格")
score = int(input("你的数学成绩为:"))
if 90 <= score <= 100:
print("优秀")
elif 80 <= score < 90:
print("良好")
elif 60 <= score < 80:
print("及格")
else:
print("不及格")