方法All返回布尔值bool，判断集合中是否所有元素都满足某一条件，通俗一点说，就是每一个元素，均符合同一个条件，它才返回真，不然返回假。
举列，创建一个model:
source code:
namespace Insus.NET.Models { public class Book { public string Publishing { get; set; } public string ISBN { get; set; } public DateTime PublicationDate { get; set; } } }
在ASP.NET MVC的视图片中，实现：
source code:
Book[] books = { new Book { Publishing = "商务出版社",ISBN="13468564394",PublicationDate=Convert.ToDateTime("2016-04-13")},
new Book { Publishing = "中华出版社",ISBN="56634565746",PublicationDate=Convert.ToDateTime("2016-01-19")},
new Book { Publishing = "海天出版社",ISBN="78234235454",PublicationDate=Convert.ToDateTime("2016-03-22")},
new Book { Publishing = "云贵出版社",ISBN="46724356756",PublicationDate=Convert.ToDateTime("2016-02-22")}
};
IEnumerable<Book> query = from bk in books
where books.All(b => b.PublicationDate > Convert.ToDateTime("2016-01-01"))
select bk;
query.ForEach(delegate (Book b)
{
WriteLiteral(string.Format("publishing: {0}; ISBN: {1}; Publication Date: {2} <br />",
b.Publishing,
b.ISBN,
b.PublicationDate.ToString("yyyy-MM-dd")));
});
更好理解，修改一下：
原文：http://www.cnblogs.com/insus/p/5385754.html