如何在保留菜单栏的情况下将表格添加到PyQt5中的中心小部件？

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QGridLayout, QWidget, QTableWidget, QTableWidgetItem

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("Table Example")
        self.setGeometry(100, 100, 500, 400)

        # 创建表格
        table = QTableWidget()
        table.setColumnCount(3)
        table.setRowCount(4)
        table.setHorizontalHeaderLabels(["Name", "Age", "Gender"])
        table.setItem(0, 0, QTableWidgetItem("John"))
        table.setItem(0, 1, QTableWidgetItem("25"))
        table.setItem(0, 2, QTableWidgetItem("Male"))
        table.setItem(1, 0, QTableWidgetItem("Alice"))
        table.setItem(1, 1, QTableWidgetItem("30"))
        table.setItem(1, 2, QTableWidgetItem("Female"))
        table.setItem(2, 0, QTableWidgetItem("Bob"))
        table.setItem(2, 1, QTableWidgetItem("35"))
        table.setItem(2, 2, QTableWidgetItem("Male"))
        table.setItem(3, 0, QTableWidgetItem("Lisa"))
        table.setItem(3, 1, QTableWidgetItem("28"))
        table.setItem(3, 2, QTableWidgetItem("Female"))

        # 创建中心小部件并设置布局
        central_widget = QWidget()
        layout = QGridLayout(central_widget)
        layout.addWidget(table, 0, 0)

        self.setCentralWidget(central_widget)

if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = MainWindow()
    window.show()
    sys.exit(app.exec_())