引用System.web和System.web.UI有什么用 记得不太清楚了.

引用System.web和System.web.UI有什么用 记得不太清楚了. using System; using System.Data; using System.Configuration; using System.Linq; using System.Web; u提示“system”中不存在类型或命名空间名称‘Ling’（缺少程序集引用吗?） System.Web.UI.ControlCollection 是什么 web guiding system怎么翻译? using System; using System.Collections; using System.ComponentModel; using System.Data; using System.Drawing; using System.Web; using System.Web.SessionState; using System.Web.UI; using System.Web.UI.WebControls; using System.Web.UI.HtmlControls; usi 有无语法错误,帮我改改谢谢using System;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System.Web.UI;using System.Web.UI.HtmlControls;using System.Web.UI.WebControls;using Sys using System; using System.Collections; using System.Configuration; using System.Data; using System.using System;using System.Collections;using System.Configuration;using System.Data;using System.Linq;using System.Web;using System.Web.Security;using System SYSTEM. system system. system system System.Web.HttpContext.Current.Request[code] ; nerve system和nervous system区别? system 和approach区别 to transplant Oracle Form based system to Java web system 怎么翻译? System怎么读?和翻译