from tkinter import Tk,Label,ttk
window = Tk()
window.resizable(0,0)
window.geometry('350x100')
window.title('文字')

def showText(*args):
try:
text = '文字1'
which = cbox.get()
if which == '文字1':
text = '文字1'
elif which == '文字2':
text = '文字2'
elif which == '文字3':
text = '文字3'
Label(window,text = text,font = ('SimHei',20)).place(x = 150,y = 15)
except Exception as e:
print('ERROR:',e)

cbox = ttk.Combobox(window,width = 15)
cbox['values'] = ['文字1','文字2','文字3']
cbox.place(x = 10,y = 10)
cbox.current(0)
cbox['state'] = 'readonly'
cbox.bind('<<ComboboxSelected>>',showText)
window.mainloop()