Error   2   Argument 1: cannot convert from 'System.Linq.IQueryable<System.Data.Objects.DataClasses.EntityCollection<WebProject.DataAccess.DatabaseModels.CmsCategory>>' to 'System.Data.Objects.ObjectQuery<WebProject.DataAccess.DatabaseModels.CmsCategory>'

int contentId = Int32.Parse(uxContentsListSelector.SelectedValue);
            var allCategories = from category in context.CmsCategories select category;
            var contentCategories = from content in context.CmsContents
                                          where content.ContentId == contentId
                                          select content.CmsCategories;
            var result = context.CmsCategories.Except(contentCategories);

var contentCategories = from content in context.CmsContents
                        from cat in content.CmsCategories
                        where content.ContentId == contentId
                        select cat;

var result = context.CmsCategories.Where(cat => !contentCategories.Any(c => c.CategoryId == cat.CategoryId));

var allCategories = from category in context.CmsCategories select category;

var allCategories = context.CmsCategories;

var contentCategories = from content in context.CmsContents
                                      where content.ContentId == contentId
                                      select content.CmsCategories;

var contentCategories = (from content in context.CmsContents
                                      where content.ContentId == contentId
                                      select content).First().CmsCategories;

var contentCategories = context.CmsContents.First(c => c.ContentId == contentId).CmsCategories;