如何将外部附件添加到通过Excel VBA发送的电子邮件中?

我有一个Excel中的VBA,用户在那里填写表单,然后单击按钮将其发送到团队电子邮件地址。我希望能够有一个框出现在发送电子邮件之前,允许用户在发送之前附加外部附件到电子邮件。

Private Sub CommandButton1_Click()
    Dim user
    Dim bookName As String
    Dim mailAns

    user = Environ("UserName")
    bookName = "General Order Form 2018" + " " + Format(CStr(Date), "dd-mm-yyyy") + "  " + user

    If MsgBox("Do you wish to send this General Order Form to Print Services?", vbYesNo) = vbNo Then
    End If

    With Sheets("Order Form 2019")
        If .CheckBox1 = True Then

            ThisWorkbook.SendMail Recipients:=Array("Print.Services@nationwide.co.uk"), Subject:="New Print Request", Returnreceipt:=True
            MsgBox "The Print Order Form has been sent to the Print Services Team, you will be contacted within 1 working day"
            ThisWorkbook.Close
            Exit Sub

        Else
            MsgBox "You have not completed the Declaration. Please accept the statements by clicking the checkbox"

        End If
    End With

End Sub