homework5

1、已装完
2、

grade=input("请输入成绩")

if int(grade)<60:
    print("不及格")

elif int(grade)<70:
    print()
elif int(grade)<90:
    print("良好")
elif int(grade)<100:
    print("优秀")

3、

x=int(input("x轴"))
y=int(input("y轴"))

if (x==0 and y==0):
    print("这是原点")
elif (x>0 and y>0):
    print("这是1")
elif (x<0 and y>0):
    print("这是2")
elif (x<0 and y<0):
    print("这是3")
else:
    print("4")
    ```
    
 4、
 ``
 grade=int(input("请输入成绩"))

if (grade<0 or grade>100):
    input("erro,try again")
else:
    if grade<60:
        print("E")
    elif grade<70:
        print("D")
    elif grade<80:
        print("C")
    elif grade<90:
        print("B")
    else:
        print("A")
 ``