尝试从实例类插入PILLOW图像

Question

我正在尝试从实例类中插入PILLOW图像。但是图像不显示。谁能帮我？谢谢！

from tkinter import *
from tkinter import ttk
from PIL import Image, ImageTk
class InsertIMG:
    def __init__(self,master,path):
        self.master=master
        self.path = path
    def add_image(self):
        load = Image.open(self.path)
        img = ImageTk.PhotoImage(load)
        l=Label(self.master,bg="white",image=img)
        l.place(x=30,y=10) 

root = Tk()
root.geometry("700x500")

fen = InsertIMG(root,'school.png')
fen.add_image()
root.mainloop()