1. 注意标准库的两种导入与使用方式，建议大家采用<库名>.<函数名>的方式。
2. 对前面的代码进行优化，用for,while,if,def实现：
   1. 画五角星
      import turtle

      for i in range(5):

          turtle.forward(150)

          turtle.right(144)

      turtle.hideturtle()

      

       

       

       

   2. 画同心圆
      import turtleturtle.bgcolor('green')for i in range(5):    turtle.up()    turtle.goto(0,-20*(i+1))    turtle.down()    turtle.circle(20*(i+1)) turtle.hideturtle()

      

       

   3. 画太阳花
      import turtleturtle.bgcolor('pink')turtle.color('green')turtle.fillcolor('yellow')turtle.begin_fill()while True:    turtle.forward(200)    turtle.left(160)    if(abs(turtle.pos()))<1:        breakturtle.end_fill()turtle.done()

      

       

   4. 画五个五角星
      import turtleturtle.bgcolor('red')turtle.color('yellow')turtle.fillcolor('yellow')def l_goto(x,y):    turtle.up()    turtle.goto(x,y)    turtle.down()def l_draw(r):        turtle.begin_fill()    for i in range(5):        turtle.forward(r)        turtle.right(144)    turtle.end_fill()l_goto(-360,190)l_draw(150)l_goto(-155,240)turtle.left(50)l_draw(50)l_goto(-90,165)turtle.left(44)l_draw(50)l_goto(-75,85)turtle.left(50)l_draw(50)l_goto(-120,50)turtle.left(50)l_draw(50)turtle.hideturtle()turtle.done()

      

       

   5. 画◇花瓣的太阳花。
      import turtledef draw_center(brad):    brad.forward(125)    brad.right(45)    brad.forward(100)    brad.right(135)def draw_flower():    window=turtle.Screen()    window.bgcolor('pink')    brad=turtle.Turtle()    brad.shape('turtle')    brad.color('green')    brad.speed('fastest')    for i in range(1,18):        draw_center(brad)        draw_center(brad)        brad.left(20)    brad.right(70)    brad.forward(325)    window.exitonclick()draw_flower()turtle.hideturtle()