var divs = html.CssSelect("div"); //all div elements
var nodes = html.CssSelect("div.content"); //all div elements with css class ‘content’
var nodes = html.CssSelect("div.widget.monthlist"); //all div elements with the both css class
var nodes = html.CssSelect("#postPaging"); //all HTML elements with the id postPaging
var nodes = html.CssSelect("div#postPaging.testClass"); // all HTML elements with the id postPaging and css class testClass
var nodes = html.CssSelect("div.content > p.para"); //p elements who are direct children of div elements with css class ‘content’
var nodes = html.CssSelect("input[type=text].login"); // textbox with css class login
We can also select ancestors of elements:
var nodes = html.CssSelect("p.para").CssSelectAncestors("div.content > div.widget");
参考资料：
http://www.cnblogs.com/shanyou/archive/2012/05/27/2520603.html
HTML Agility Pack 搭配 ScrapySharp，彻底解除Html解析的痛苦
原文：http://www.cnblogs.com/lihuali/p/5984598.html