题目：利用ellipse 和 rectangle 画图。。
程序分析：无。
程序源代码：
#!/usr/bin/python
# -*- coding: UTF-8 -*-
if __name__ =='__main__':
fromTkinterimport*
canvas =Canvas(width =400,height =600,bg ='white')
left =20
right =50
top =50
num =15
for i in range(num):
canvas.create_oval(250- right,250- left,250+ right,250+ left)
canvas.create_oval(250-20,250- top,250+20,250+ top)
canvas.create_rectangle(20-2* i,20-2* i,10*(i +2),10*( i +2))
right +=5
left +=5
top +=10
canvas.pack()
mainloop()
