看原始响应文本（例如，使用Fiddler）。如果标题是不存在的，没有任何的C＃代码量会使其出现。 :)从你已经证明什么，似乎头是不是在回应

Look at the raw response text (e.g., with Fiddler). If the header isn't there, no amount of C# code is going to make it appear. :) From what you've shown, it seems the header isn't in the response.

更新：当我去：的 http://twitter.com/account/rate_limit_status.xml 没有 X-RateLimit限额头。但是，当我去 http://twitter.com/statuses/public_timeline.xml ，它的存​​在。因此，我认为你只需要使用不同的方法。

Update: When I go to: http://twitter.com/account/rate_limit_status.xml there is no X-RateLimit-Limit header. But when I go to http://twitter.com/statuses/public_timeline.xml, it's there. So I think you just need to use a different method.

它仍然说150，但！