20以内加法演示

from tkinter import *
import random
root = Tk()
root.title("加法演示")
root.geometry("600x300")
def repeat():
    global timer
    rand = random.randint(1,10)
    cv.itemconfigure('rand',text='   '+str(rand))
    rand1 = random.randint(1,10)
    cv1.itemconfigure('rand1',text='   '+str(rand1))
    timer = root.after(100,repeat)
    s=rand+rand1
    cv2.itemconfigure(