C#读取Excel批注

Microsoft.Office.Interop.Excel.Application myobject = new Microsoft.Office.Interop.Excel.Application();
Microsoft.Office.Interop.Excel._Workbook m_objBook = myobject.Workbooks.Open(@"H:\\aa.xlsx", m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt, m_objOpt);
m_objsheets = m_objBook.Worksheets;
m_objSheet = (_Worksheet)m_objsheets.get_Item("Sheet1");
string pos = "A1";
m_objRange = m_objSheet.get_Range(pos, m_objOpt);
string s = m_objRange.Comment.Shape.AlternativeText;
m_objBook.Close(m_objOpt, m_objOpt, m_objOpt);
myobject.Workbooks.Close();
myobject.Quit();
System.Runtime.InteropServices.Marshal.ReleaseComObject(m_objBook);
System.Runtime.InteropServices.Marshal.ReleaseComObject(myobject);
m_objBook = null;
myobject = null;
GC.Collect();
foreach (System.Diagnostics.Process p in System.Diagnostics.Process.GetProcesses())
{
if (p.ProcessName.ToUpper() == "EXCEL")
{
p.Kill();
}
}