运行如下代码，点击按钮Greet后label框内显示“Hello, World!”字样。（ ）
import tkinter as tk def greet(): label.config(text="Hello, World!") root = tk.Tk() label = tk.Label(root, text="") button = tk.Button(root, text="Greet", command=greet) label.pack() button.pack() root.mainloop()
