entity framework groupby解决办法

entity framework groupby
弄了一个晚上的groupby,还是弄不出来，试了几种方法都不行，只有请教大侠了，以下是我写的其中几个方法，都不行
  string sql = "select value it from Entities.Subject as it group by ID";
  IQueryable<Entity.Subject> queryTab = context.CreateQuery<Entity.Subject>(sql);
  //IQueryable<Entity.Subject> qq = from custom in context.Subject.where("it.ID=1").GroupBy("it.ID") select custom;
  string abd="aa";
  //IQueryable<Entity.Subject> qq =from custom in context.Subject where custom.Teacher==abd select custom group custom by custom.Teacher;
  IQueryable<Entity.Subject> qqa = from custom in context.Subject where custom.Teacher == abd group custom by custom.Teacher;

急急

[解决办法]
这个是.net的技术应该到.net版本问。