Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" (ByVal hwnd As Long, _
ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, _
ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long

Private Sub Command1_Click()
ShellExecute Me.hwnd, "open", "c:a.doc", vbNullString, vbNullString, 3
End Sub

Private Sub Command2_Click()
'在VBA引用中要勾选 Microsoft Word 11.0 Object Library
    Dim WordApp As Word.Application
    Set WordApp = New Word.Application
    WordApp.Documents.Add ("c:a.doc")
    WordApp.Visible = True
    Set WordApp = Nothing
End Sub