在用了这段代码将doc文件导出成txt文件后，如何关闭winword.exe进程啊？

[dnyz]

Word.ApplicationClass ThisApplication = new Word.ApplicationClass();
object missingValue = Type.Missing;
object True = true;

object fileName;

if(openFile.ShowDialog()==DialogResult.OK)
{

fileName = openFile.FileName;
Word.Document ThisDocument = ThisApplication.Documents.Open(ref fileName, ref missingValue,
ref True, ref missingValue, ref missingValue, ref missingValue,
ref missingValue, ref missingValue, ref missingValue,
ref missingValue, ref missingValue, ref missingValue,
ref missingValue, ref missingValue, ref missingValue);

object newFile, format;
newFile = @"D:\test.txt";
format = Word.WdSaveFormat.wdFormatText;

ThisDocument.SaveAs(ref newFile,ref format,ref missingValue,ref missingValue,
ref missingValue,ref missingValue,ref missingValue,ref missingValue,ref missingValue,
ref missingValue,ref missingValue,ref missingValue,ref missingValue,ref missingValue,
ref missingValue,ref missingValue);

ThisDocument.Close(ref missingValue, ref missingValue, ref missingValue);
}


程序能运行，但是就是运行后，winword.exe进程总留在内存里，该如何关闭呢？

[烤火的鱼]

Word.Application myApp=new Word.ApplicationClass();
object obFileName=(object)this.m_WordFileName;
Word.Document myDoc=null;
……
myApp.Quit(ref Nothing, ref Nothing, ref Nothing);