大家看下，这个取网页源代码的AJAX到底怎么搞？

http://s.jipiao.trip.taobao.com/flight_search_result.htm?_fmh.fl._0.s=%B1%B1%BE%A9&=BJ&_fmh.fl._0.e=%B9%E3%D6%DD&=CAN&_fmh.fl._0.t=0&_fmh.fl._0.sta=2011-12-18&_fmh.fl._0.r=yyyy-mm-dd请问下，当点击那个选择时，出现的AJAX数据，抓包得知，呆了个UA参数（下面那个），http://s.jipiao.trip.taobao.com/search/search.htm?type=button&depCity=BJS&depCityName=北京&arrCity=CAN&arrCityName=广州&depDate=2011-12-18&tripType=0&agentIds=&qijian=&autoBook=&cabinClass=&searchSource=&callback=YUI.Env.JSONP.yui_3_3_0_1_1324141297327668&flightNo=CA1351&ua=212N5fmXZX4WJf%2BXZTzVZf4WPs%3D%7CN5TmN4SDKd66AMm4CdToQJDmTvGjAsKlG9XoMfs%3D%7CN5XmN5T6W4r7XZLmVZ%2F6QJf4Xp%2FmXZTyXIr7XJT%2BQJf4VJbmVZ%2F8Mfs%3D%7CN5f4QIT7X5T%2BXZL7Xp%2FzXZT%2BVpbkVZ74VZL6XZD8VZH8WJTzVYSX%7CN5f6QISRW5P4XYqWTpf5XpL7WJb9WJ78VJC2XIj%2FXp74X5H5VJ%2F8XZfyXp74MITmXfvoMQ%3D%3D%7CN5f6QISRW5P4XYqWTpf5XpL7WJb9WJ78VJC2XIj%2FXp74X5H5VJ%2F8XZfyXp74MITmXfvoMQ%3D%3D%7CN5f6QISRW5P4XYqWTpf5XpL7WJb9WJ78VJC2XIj%2FXp74X5H5VJ%2F8XZfyXp74MITmXfvoMQ%3D%3D%7CN5LmN4ToQJD%2FWIr7W5HmXp%2F8VPuX%7CN5LmN4ToQJD%2BW4r7VJPmX5b8XvuX%7CN5LmN4SzGc%2BVX%2Fn5M5aVXfn7X5T%2BXZL7Xp%2F9X5T9WZP4Tor8WJHmXZ7%2FQJX7XpOXMQ%3D%3D%7CN5LmN4SzGc%2BVX%2Fn5M5aVXfn7X5T%2BXZL7Xp%2F9X5T9WZP4Tor8WJHmXZ7%2FQJX7WJaXMQ%3D%3D%7CN5LmN4SzGc%2BVX%2Fn5M5aVXfn7X5T%2BXZL7Xp%2F9X5T9WZP4Tor8WJHmXZ7%2FQJX7W5SXMQ%3D%3D%7CN5PmN4SzGc%2BVX%2Fn5M5aVXfn7X5T%2BXZL7Xp%2F9X5T9Wpf9ToqRWp77QJP6VPvmXIroTor%2FWp%2F6WvuX%7CN5PmN4SzGc%2BVX%2Fn5M5aVXfn7X5T%2BXZL7Xp%2F9X5T9WpL%2FToqRXZbzW4r%2BXJPmXZb%2BXor5VZTmWpDmXpeXQJbmToTmW5%2F%2BWp6XMQ%3D%3D
是一个什么验证码之类的？
这个参数应该怎么搞？谢谢大家了，我使用这个UA参数POST提交时，第一次修改（把广州修改上海）提交，没有错误，第一次修改（把广州修改长沙）提交，没有错误，第三次修改时候，就错误了，我知道很明显是UA参数错误了，该怎么解决？