Tkinter窗口无法用新画布打开

Question

我试图关闭一个窗口，然后在一个类中打开一个新窗口，但是第二个窗口没有打开。

谁能告诉我什么不起作用。

（代码制作的游戏会随机获得2个数字，并要求您将它们加在一起，然后显示一条消息，说明您是对还是错）

代码在其自己的窗口中，而不在类中起作用。

Self.G是主菜单屏幕。

此处的代码：

def start(self):
    self.G.destroy()
    self.game()
## The game playing ##
def game(self):



    def Questions(self):
        number1 = random.randrange(1,25)
        number2 = random.randrange(1,50)
        answer = number1 + number2
        prompt = ("Add " + str(number1) + " and " + str(number2))
        label1 = Label(self.root, text=prompt, width=len(prompt), bg='yellow')
        label1.pack()
        return answer

    def start(self):
        global answer
        answer = Questions()

        def Submit(answer, entryWidget):
             """ Display the Entry text value. """
             print(answer)

             if entryWidget.get().strip() == "":
                 messagebox.showerror("Tkinter Entry Widget", "Please enter a number.")

             if answer != int(entryWidget.get().strip()):
                 incorrect = ('Thats incorrect!')
                 boxInco = Label(root, text=incorrect, width=len(incorrect), bg='orange')
                 boxInco.pack()


             else:
                 Textcorrect = ('Correct!')
                 CorrectMessage = Label(root, text=Textcorrect, width=len(Textcorrect), bg='orange')
                 CorrectMessage.pack()


        # creates a Tkinter window
        self.root = Tk()

        self.root.title("Math Quiz")
        self.root["padx"] = 40
        self.root["pady"] = 20   

        # Creates a text frame to hold the text Label and the Entry widget
        textFrame = Frame(self.root)

        #Creates a Label in textFrame
        entryLabel = Label(textFrame)
        entryLabel["text"] = "Answer:"
        entryLabel.pack(side=LEFT)

        # Creates an Entry Widget in textFrame
        entryWidget = Entry(textFrame)
        entryWidget["width"] = 50
        entryWidget.pack(side=LEFT)

        textFrame.pack()

        #instructions     
        directions = ('Click start to begin. You will be asked a series of questions.')
        instructions = Label(root, text=directions, width=len(directions), bg='orange')
        instructions.pack()



        Sub = lambda: Submit(answer, entryWidget)
        #stopwatch = lambda: start(answer)

        # create needed widgets
        label = Label(self.root, text='0.0')
        btn_submit = Button(self.root, text="Submit", command = Sub)
        btn_start = Button(self.root, text="Start", command = start)
        btn_submit.pack()
        btn_start.pack()
        label.pack()


        # start the event loop
        self.root.mainloop()

目前，它删除了第一个窗口，但第二个窗口什么也不做，没有错误消息，没事。