var parameter = Expression.Parameter(typeof(A), "a");
            var member = Expression.Field(parameter, "b");
            member = Expression.Field(member, "id");
            var constant = Expression.Constant(9);
            var bin = Expression.GreaterThan(member, constant);
            var lambda = Expression.Lambda<Func<A, bool>>(bin, parameter);
            h.Where(lambda.Compile()).ToList();

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace Test
{
    public class A
    {
        public int Id;
        public string Name;
        public B b;
    }
    public class B
    {
        public int Id;

    }

    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        List<A> h = new List<A>(){
            new A(){ b = new B(){ Id = 1}},
            new A(){ b = new B(){ Id = 3}},
            new A(){ b = new B(){ Id = 11}},
            new A(){ b = new B(){ Id = 13}},
            new A(){ b = new B(){ Id = 12}},
            new A(){ b = new B(){ Id = 7}},
            new A(){ b = new B(){ Id = 9}}
        };

        private void Form1_Load(object sender, EventArgs e)
        {
            var parameter = Expression.Parameter(typeof(A), "a");
            var member = Expression.Field(parameter, "b");
            member = Expression.Field(member, "id");
            var constant = Expression.Constant(9);
            var bin = Expression.GreaterThan(member, constant);
            var lambda = Expression.Lambda<Func<A, bool>>(bin, parameter);

            h.Where(lambda.Compile()).ToList().ForEach(n => MessageBox.Show(n.b.Id.ToString()));
        }
    }
}