【qt5-两位数加法练习器】小制作---使用qt5制作小学计算题

通过编写程序，编出一个适用小学加法计算题的小练习程序。

#!/usr/bin/python3
# -*- coding: utf-8 -*-

"""
Py40 PyQt5 tutorial

This program centers a window
on the screen.

author: Jan Bodnar
website: py40.com
last edited: January 2015
"""

import sys

from PyQt5.QtCore import Qt
from PyQt5.QtWidgets import QWidget, QDesktopWidget, QApplication, QPushButton, QVBoxLayout, QLineEdit, QHBoxLayout, 
    QLabel
import random

from pyqt5_plugins.examplebuttonplugin import QtGui


class Example(QWidget):

    def __init__(self):


        super().__init__()
        self.score = 0
        self.num1 = random.randint(1,20)

        self.num2 = random.randint(1,20)

        self.initUI()

    def initUI(self):
        self.resize(500, 200)
        self.center()
        self.btn()

        self.setWindowTitle('两位数加法运算')
        self.show()

    # 控制窗口显示在屏幕中心的方法
    def center(self):
        # 获得窗口
        qr = self.