C#4做COM的时候需要调用Marshal.ReleaseComObject吗？

using System;
using System.Runtime.InteropServices;

class Program
{
    static void Main(string[] args)
    {
        Type comType = Type.GetTypeFromProgID("Excel.Application");
        dynamic excel = Activator.CreateInstance(comType);
        try
        {
            excel.Visible = true;
            excel.Workbooks.Add();
            excel.Cells[1, 1].Value = "Hello, World!";
        }
        finally
        {
            Marshal.ReleaseComObject(excel.Workbooks);
            Marshal.ReleaseComObject(excel);
        }
    }
}