画一个太极八卦图，效果如下图
 
要求：
1.大圆坐标(0,-200)，半径200
2.黑色大半圆：半径100
3.白色大半圆：半径100
4.黑色小半圆：半径25，坐标(0,-100)
5.白色小半圆：半径25，坐标(0,100)

参考代码

import turtle

#最大圆
turtle.penup()
turtle.goto(0,-200)
turtle.pendown()
turtle.circle(200)

#移动到最上方
turtle.penup()
turtle.goto(0,200)
turtle.left(180)
turtle.pendown()

#黑色大半圆
turtle.fillcolor('black')
turtle.begin_fill()
turtle.circle(100,360)
turtle.end_fill()
turtle.fillcolor('black')
turtle.begin_fill()
turtle.left(180)
turtle.circle(-200,180)
turtle.end_fill()

#白色大半圆
turtle.home()
turtle.fillcolor('white')
turtle.begin_fill()
turtle.circle(-100,180)
turtle.pencolor('white')
turtle.circle(-100,180)
turtle.end_fill()

#白色小圆
turtle.penup()
turtle.goto(0,100)
turtle.pendown()
turtle.dot(50,'white')

#黑色小圆
turtle.penup()
turtle.goto(0,-100)
turtle.pendown()
turtle.dot(50,'black')

turtle.hideturtle()