SQL Server 2005“公共”数据库角色似乎不适用？

I have a SQL Server 2005 database that I'm trying to access as a limited user account, using Windows authentication. I've got BUILTIN\Users added as a database user (before I did so, I couldn't even open the database). I'm working under the assumption that everybody is supposed to have permissions for the "public" role applied to them, so I didn't do anything with role assignment. Under tblFoo, I can use the SSMS Properties dialog (Permissions page) to add "public", then set explicit permissions. Among these is "Grant" for SELECT. But runningI have a SQL Server 2005 database that I'm tryi