条件、循环、函数定义 练习

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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
      turtle.speed(10)
      turtle.color('gray')
      turtle.fillcolor('yellow')
      turtle.begin_fill()
      for i in range(5):
          turtle.forward(200)
          turtle.right(144)
          if(abs(turtle.pos()))<1:
              break
      turtle.end_fill()

      

   2. 画同心圆

      import turtle
      turtle.speed(10)
      for i in range(1,5):    
          turtle.up()
          turtle.goto(0,(-20*i))
          turtle.down()
          turtle.circle(20*i)

      

   3. 画太阳花

      import turtle
      turtle.speed(10)
      turtle.color('gray')
      turtle.fillcolor('pink')
      turtle.begin_fill()
      for i in range(38):
          turtle.forward(200)
          turtle.left(170)
          if(abs(turtle.pos()))<1:
              break
      turtle.end_fill()

      

   4. 画五个角星

      import turtle
      turtle.speed(10)
      turtle.bgcolor('red')
      
      def goto(x,y):
          turtle.up()
          turtle.goto(x,y)
          turtle.down()
      
      def draw(r):
          turtle.color('yellow')
          turtle.fillcolor('yellow')
          turtle.begin_fill()
          for i in range(5):
              turtle.forward(r)
              turtle.right(144)
          turtle.end_fill()
      
      goto(-550,200)
      draw(230)
      
      goto(-260,280)
      turtle.left(45)
      draw(60)
      
      goto(-165,175)
      turtle.left(50)
      draw(60)
      
      goto(-185,100)
      turtle.right(95)
      draw(60)
      
      goto(-260,0)
      turtle.left(45)
      draw(60)
      
      turtle.hideturtle()

      

   5. 画◇花瓣的太阳花。

      import turtle
      turtle.speed(10)
      turtle.color('red')
      turtle.fillcolor('coral') 
      turtle.begin_fill()
      for i in range(36):      
          for j in range(2):        
              turtle.forward(100)
              turtle.right(45)
              turtle.forward(100)
              turtle.right(135)      
          turtle.right(10)
      turtle.right(90)
      turtle.forward(400)
      turtle.end_fill()