C# webrequest 抓取数据时，多个域Cookie的问题

最近研究了下如何抓取为知笔记的内容，在抓取笔记里的图片内容时，老是提示403错误，用Chorme的开发者工具看了下：

这里的Cookie来自两个域，估计为知那边是验证了token(登录后才能获取到token)

下载图片的代码：

var path = "https://note.wiz.cn/" + str.TrimStart('/');
var extension = Path.GetExtension(path);
var filepath = AppPath.Combine("Images/" + DateTime.Now.Ticks + extension);

const string userAgent ="Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.76 Safari/537.36";
const string accept = "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8";
const string acceptLanguage = "zh-CN,zh;q=0.8";
const string acceptEncoding = "gzip,deflate,sdch";
var cookieContainer = new CookieContainer();
var cookie = new Cookie
{
    Name = "token".Trim(),
    Value = Token,
    Domain = ".wiz.cn".Trim() //设置cookie域
};
cookieContainer.Add(cookie);
string[] cookiesArr = txtCookie.Text.Split(';');
foreach (string s in cookiesArr)
{
    string[] keyValuePair = s.Split('=');
    if (keyValuePair.Length > 1)
    {
        cookie = new Cookie
                       {
                           Name = keyValuePair[0].Trim(),
                           Value = keyValuePair[1].Trim(),
                           Domain = "note.wiz.cn" //设置cookie域
                       };
        cookieContainer.Add(cookie);
    }
}

var newUri = new Uri(path);
var webRequest = (HttpWebRequest)WebRequest.Create(newUri);
webRequest.Timeout = 20000;
//webRequest.CookieContainer = cookieContainer;
webRequest.UserAgent = userAgent;
webRequest.Accept = accept;
webRequest.Headers["Accept-Language"] = acceptLanguage;
webRequest.Headers["Accept-Charset"] = acceptEncoding;
webRequest.Headers["Accept-Encoding"] = acceptEncoding;
webRequest.KeepAlive = true;
webRequest.Headers["Cache-Control"] = "no-cache";
webRequest.Headers["Upgrade-Insecure-Requests"] = "1";
webRequest.Headers["Pragma"] = "no-cache";
webRequest.Headers["Cookie"] = "token=" + Token + ";" + txtCookie.Text.Trim();//todo: Cookie 要这样赋值，不能用CookieContainer？？

webRequest.Referer = newUri.AbsoluteUri;
HttpWebResponse rsp = (HttpWebResponse)webRequest.GetResponse();

Stream stream = null;
stream = rsp.GetResponseStream();
Image.FromStream(stream).Save(filepath);

// 释放资源
if (stream != null) stream.Close();
if (rsp != null) rsp.Close();

奇怪的是：用 webRequest.CookieContainer = cookieContainer; 来跟cookie赋值，token参数总是赋不上，

后面改为：webRequest.Headers["Cookie"] = "token=" + Token + ";" + txtCookie.Text.Trim(); 就可以了，

CookieContainer 不是支持多个域的cookie吗，难到跨域Cookie只能webRequest.Headers["Cookie"]这样赋值吗？ 没弄明白，有知道的童鞋不吝赐教。