看来wget之前也存在此类问题，于是继续搜索标准，输出如下:The presence of a message body in a response depends on both the request method to which it is responding and the response status code . Responses to the HEAD request method never include a message body because the associated response header fields ， if present， indicate only what their values would have been if the request method had been GET . 2xx responses to a CONNECT request method switch to tunnel mode instead of having a message body. All 1xx ， 204 ， and 304 responses do not include a message body. All other responses do include a message body， although the body might be of zero length.
本文节选自霍格沃兹测试开发学社内部教材获取更多相关资料点击：Redirecting...A 发送请求，然后等待 B 的响应，同时开始超时计时，如果在超时时间内成功接收到响应，则结束等待和计时。如果到了超时时间还没有接收到响应，则结束等待同时此次通讯失败，这个过程叫做请求超时。
