print( "a" * 3 )

print(10<=3 or 5>2)

a, b, c = 2, 3, 7

d = (b + c) – a * a

print( d )

str1 = 'key'

str2 = 'board’

print(str1 + str2)

a = 1

if a > 0:

    print("产品合格")

else:

    print("产品不合格")

age = int(input("年龄："))

if age < 4:

    print("免费")

elif age < 18:

    print("4元")

else:

    print("8元")

a = eval( "3.0+2.0" )

tina = turtle.Turtle( )

for  i  in range(4) : 

    tina.forward(100) 

    tina.left(90) 

tina.hideturtle( )