我正在尝试根据Tkinter下拉菜单添加输入字段，但我不确定我是否正确执行此操作。当我在其中一个下拉菜单中选择一个选项时，我没有弹出任何新的输入字段。代码就是我到目前为止所拥有的。我也尝试将if语句放在外部函数中并在OptionMenu中放置一个命令，但它仍然无效。
from Tkinter import *
def callback():
numQues = int(E1.get())
i = 0
while i <= numQues:
variable = StringVar(top)
variable.set("Questions Type") # default value
w = OptionMenu(top, variable, "Short Answer", "Multiple Choice", "Fill in the Blank",
"True of False", "Matching", "Ordering")
w.grid(row = i*2+2, column=0)
ques = StringVar(top, value='Question')
ans = StringVar(top, value='Answer')
choice = StringVar(top, value='Answer Choices')
if variable.get() == "Short Answer":
q = Entry(top, bd = 5, textvariable = ques)
q.grid(row=i*2+2, column = 2, columnspan=2)
a = Entry(top, bd = 5, textvariable = answ)
a.grid(row=i*2+2, column = 4, columnspan=2)
if variable.get() == "Multiple Choice":
q = Entry(top, bd = 5, textvariable = ques)
q.grid(row=i*2+2, column = 2, columnspan=2)
c = Entry(top, bd = 5, textvariable = answ)
c.grid(row=i*2+2, column = 4, columnspan=2)
a = Entry(top, bd = 5, textvariable = answ)
a.grid(row=i*2+2, column = 6, columnspan=2)
if variable.get() == "True or False":
q = Entry(top, bd = 5, textvariable = ques)
q.grid(row=i*2+2, column = 2, columnspan=2)
a = Entry(top, bd = 5, textvariable = answ)
a.grid(row=i*2+2, column = 6, columnspan=2)
if variable.get() == "Fill in the Blank":
q = Entry(top, bd = 5, textvariable = ques)
q.grid(row=i*2+2, column = 2, columnspan=2)
a = Entry(top, bd = 5, textvariable = answ)
a.grid(row=i*2+2, column = 4, columnspan=2)
if variable.get() == "Ordering":
q = Entry(top, bd = 5, textvariable = ques)
q.grid(row=i*2+2, column = 2, columnspan=2)
a = Entry(top, bd = 5, textvariable = answ)
a.grid(row=i*2+2, column = 4, columnspan=2)
i = i+1
top = Tk()
top.geometry("600x600")
top.title("eCampus Quiz Developer")
L1 = Label(top, text="How many questions will the quiz be?")
L1.grid(row=0, column=0)
E1 = Entry(top, bd = 5)
E1.grid(row=0, column=1)
MyButton1 = Button(top, text="Submit", width=10, command=callback)
MyButton1.grid(row=1, column=1)
top.mainloop()