from PySide2 import QtWidgets

class MyComBox(QtWidgets.QWidget):
    def __init__(self):
        QtWidgets.QWidget.__init__(self)
        comboxText = ["Hi", "Bye", "Give me a warning"]
        self.comBox = QtWidgets.QComboBox(self)
        self.comBox.addItems(comboxText)
        self.comBox.move(20,40)
        self.setGeometry(100, 100, 200, 100)
        self.show()

if __name__ == '__main__':
    app = QtWidgets.QApplication([])
    combo = MyComBox()
    app.exec_()