1.画一组同切圆
>>> import turtle
>>> turtle.circle(10)
>>> turtle.circle(30)
>>> turtle.circle(50)
>>> turtle.circle(70)
2. 画一组同心圆
>>> turtle.circle(20)
>>> turtle.up()
>>> turtle.goto(0,-20)
>>> turtle.down()
>>> turtle.circle(40)
>>> turtle.up()
>>> turtle.goto(0,-90)
>>> turtle.down()
>>> turtle.circle(110)
3. 画一个五角星
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
4. 画一个黄色实心五角星
>>> turtle.color('yellow')
>>> turtle.fillcolor('yellow')
>>> turtle.begin_fill()
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
>>> turtle.right(144)
>>> turtle.forward(50)
>>> turtle.end_fill()
