新手请教python抽奖程序

import tkinter
import random
import threading
import time
import csv    #加载csv包便于读取csv文件
# 初始化窗口
root = tkinter.Tk()
root.title("上海克比年会抽奖名单")
root.geometry('500x500+400+200')
root.resizable(False, False)
root.flag = True
# 三个Lable标签
csv_file=open('c:/12.csv')    #打开csv文件
csv_reader_lines = csv.reader(csv_file)   #逐行读取csv文件
students = [ ]    #创建列表准备接收csv各行数据
for one_line in csv_reader_lines:
    students.append(one_line)  # 将读取的csv分行数据按行存入列表‘date’中
students.append(one_line)

def switch():
    root.flag = True
    while root.flag:
        i = random.randint(0, len(students) - 1)
        first['text'] = second['text']
        second['text'] = third['text']
        third['text'] = students[i]
        time.sleep(0.001)

first = tkinter.Label(root, text='', font=("宋体", 20, "normal"))
first.place(x=100, y=100, width=300, height=100)

second = tkinter.Label(root, text='', font=("宋体", 20, "normal"))
second['fg'] = 'red'
second.place(x=100, y=200, width=300, height=100)

third = tkinter.Label(root, text='', font=("宋体", 20, "normal"))
third.place(x=100, y=300, width=300, height=100)

# 开始按钮
def butStartClick():
    t = threading.Thread(target=switch)
    t.start()

#设置几个奖项
btnStart = tkinter.Button(root, text='开始', command=butStartClick)
btnStart.place(x=20, y=30, width=80, height=20)
one = tkinter.Button(root, text='一等奖', command=butStartClick)
one.place(x=110, y=30, width=80, height=20)
two = tkinter.Button(root, text='二等奖', command=butStartClick)
two.place(x=210, y=30, width=80, height=20)
three= tkinter.Button(root, text='三等奖', command=butStartClick)
three.place(x=310, y=30, width=80, height=20)

# 结束按钮
def btnStopClick():
    root.flag = False

butStop = tkinter.Button(root, text='停止', command=btnStopClick)
butStop.place(x=410, y=30, width=80, height=20)

# 启动主程序
root.mainloop()