大佬们，为什么运行完毕后像图片上一样，按键盘也没反应，下面也没报错

import math
import pygame, sys
from pygame.locals import *
pygame.init()
screen = pygame.display.set_mode((600, 500))
pygame.display.set_caption("The Pie Game = Press 1,2,3,4")  # 设置当前窗口的标题栏
myfont = pygame.font.Font(None, 60)
color = 200, 80, 60
width = 4
x = 300
y = 250
radius = 200
position = x - radius, y - radius, radius * 2, radius * 2
piece1 = True
piece2 = False
piece3 = False
piece4 = False
# clear the screen
screen.fill((200, 200, 200))  # 填充背景颜色
while True:
    for event in pygame.event.get():
        if event.type == QUIT:  # 按下关闭按钮窗口关闭
            sys.exit()
        if event.type == KEYUP:  # 先判断event类型再进行使用（https://segmentfault.com/q/1010000012828917）
            if event.key == pygame.K_ESCAPE:
                sys.exit()
            elif event.key == pygame.K_1:
                piece1 = True
            elif event.key == pygame.K_2:
                piece2 = True
            elif event.key == pygame.K_3:
                piece3 = True
            elif event.key == pygame.K_4:
                piece4 = True
    # draw the four screen
    textImg1 = myfont.render("1", True, color)
    screen.blit(textImg1, (x + radius / 2 - 20, y - radius / 2))
    textImg1 = myfont.render("2", True, color)
    screen.blit(textImg1, (x - radius / 2, y - radius / 2))
    textImg1 = myfont.render("3", True, color)
    screen.blit(textImg1, (x - radius / 2, y + radius / 2 - 20))
    textImg1 = myfont.render("4", True, color)
    screen.blit(textImg1, (x + radius / 2 - 20, y + radius / 2 - 20))
    # should the pieces be drawn?
    if piece1:
        start_angle = math.radians(0)
        end_angle = math.radians(90)
        pygame.draw.arc(screen, color, position, start_angle, end_angle, width)
        pygame.draw.line(screen, color, (x, y), (x, y - radius), width)
        pygame.draw.line(screen, color, (x, y), (x + radius, y), width)
    if piece2:
        start_angle = math.radians(90)
        end_angle = math.radians(180)
        pygame.draw.arc(screen, color, position, start_angle, end_angle, width)
        pygame.draw.line(screen, color, (x, y), (x, y - radius), width)
        pygame.draw.line(screen, color, (x, y), (x - radius, y), width)
    if piece3:
        start_angle = math.radians(180)
        end_angle = math.radians(270)
        pygame.draw.arc(screen, color, position, start_angle, end_angle, width)
        pygame.draw.line(screen, color, (x, y), (x - radius, y), width)
        pygame.draw.line(screen, color, (x, y), (x, y + radius), width)
    if piece4:
        start_angle = math.radians(270)
        end_angle = math.radians(360)
        pygame.draw.arc(screen, color, position, start_angle, end_angle, width)
        pygame.draw.line(screen, color, (x, y), (x, y + radius), width)
        pygame.draw.line(screen, color, (x, y), (x + radius, y), width)
    # is the pie finished?
    if piece1 and piece2 and piece3 and piece4:
        color = 0, 255, 0
    pygame.display.update()  # 更新用户显示窗口