import turtle
# 设置画笔
t = turtle.Pen()
t.pencolor("blue")
for a in range (2,50,2):
# 画圆
  t.circle(a)
# 将画笔抬起
t.up()
# 移动画笔
t.goto(20, 0)
# 将画笔放下
t.down()
# 画圆
t.circle(10)