C# xpath 查询问题

Question

我要查询 ：
条件：title='Harry Potter'   一定要注意，title值有单引号如何处理
目标：book的属性@category值是多少
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book category="COOKING">
  <title lang="en">'Everyday Italian'</title>
  <author>Giada De Laurentiis</author>
  <year>2005</year>
  <price>30.00</price>
</book><book category="CHILDREN">
  <title lang="en">'Harry Potter'</title>
  <title lang="en">Everyday Italian</title>
  <author>J K. Rowling</author>
  <year>2005</year>
  <price>29.99</price>
</book>已经有的方法using System.Xml;
using System.Xml.XPath;        public string GetData(string strsql)
        {
            XPathNavigator nav;
            XPathDocument docNav;
            XPathNodeIterator NodeIter;            string strRetrun = string.Empty;
            nav = docNav.CreateNavigator();
            strExpression = "";//在这儿写查询语句
            MessageBox.Show(strExpression);
            NodeIter = nav.Select(strExpression);
            while (NodeIter.MoveNext())
            {
                strRetrun += NodeIter.Current.Value;
            };
            return strRetrun;
        }
或者给更好的建议

Answer 1

            string _Path = "\"'Harry Potter'\"";            XmlNodeList _List = _Document.SelectNodes("bookstore/book/title[.="+_Path+"]");