作业4

import turtle
turtle.pensize(10)
# 绘制第一道彩虹
turtle.pencolor("red")
turtle.left(90)
turtle.circle(10,180)
# 绘制第二道彩虹
turtle.pencolor("orange")
turtle.left(180)
turtle.penup()
turtle.goto(10,0)
turtle.pendown()
turtle.circle(20,180)
# 绘制第三道彩虹
turtle.pencolor("yellow")
turtle.left(180)
turtle.penup()
turtle.goto(20,0)
turtle.pendown()
turtle.circle(30,180)
# 绘制第四道彩虹
turtle.pencolor("green")
turtle.left(180)
turtle.penup()
turtle.goto(30,0)
turtle.pendown()
turtle.circle(40,180)
# 绘制第五道彩虹
turtle.pencolor("cyan")
turtle.left(180)
turtle.penup()
turtle.goto(40,0)
turtle.pendown()
turtle.circle(50,180)
# 绘制第六道彩虹
turtle.pencolor("blue")
turtle.left(180)
turtle.penup()
turtle.goto(50,0)
turtle.pendown()
turtle.circle(60,180)
# 绘制第七道彩虹
turtle.pencolor("purple")
turtle.left(180)
turtle.penup()
turtle.goto(60,0)
turtle.pendown()
turtle.circle(70,180)


turtle.done()