$ curl -I "http://www.suning.com"
HTTP/1.1 200 OK
Date: Sun, 31 Jul 2011 11:56:15 GMT
Server: IBM_HTTP_Server/7.0.0.13 (Unix)
Pragma: No-cache
Cache-Control: no-cache,no-store,max-age=0
Expires: Thu, 01 Jan 1970 00:00:00 GMT

1. 时间比北京时间晚了4分钟
2. Expires很奇怪。。