Linq多层查询问题

先看代码，大致代码如下：List alist=new List();List blist=new List();B b=new B();b.MD5="12572195";blist.add(b);A a=new A();a.BList=blist;alist.add(a);我要查询alist里的A元素的Blist里的元素的MD5属性为"12572195"的元素，使用Linq查询

List<A> alist = new List<A>();
    List<B> blist = new List<B>();
    B b = new B();
    b.MD5 = "12572195";
    blist.Add(b);
    A a = new A();
    a.BList = blist;
    alist.Add(a);

    var result = from e in a.BList
    where e.MD5 == "12572195"
    select e;

    foreach (var item in result)
    {
    Console.WriteLine(item.MD5);
    }