diff --git a/LinqStudy.Test/LinqToObject/BaseTest.cs b/LinqStudy.Test/LinqToObject/BaseTest.cs
index 18b8b3d..cecec15 100644
--- a/LinqStudy.Test/LinqToObject/BaseTest.cs
+++ b/LinqStudy.Test/LinqToObject/BaseTest.cs
@@ -10,7 +10,9 @@ using Xunit;
 namespace LinqStudy.Test.LinqToObject
 {
     /// <summary>
-    /// 基本项测试
+    /// 查询运算符：本质定义在下面程序集中的扩展方法，少量静态方法。
+    /// System.Linq.Enumerable
+    /// System.Linq.Queryable
     /// </summary>
     public class BaseTest
     {
diff --git a/LinqStudy.Test/LinqToObject/ConvertTest.cs b/LinqStudy.Test/LinqToObject/ConvertTest.cs
new file mode 100644
index 0000000..1ad9e06
--- /dev/null
+++ b/LinqStudy.Test/LinqToObject/ConvertTest.cs
@@ -0,0 +1,22 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+
+using Xunit;
+
+namespace LinqStudy.Test.LinqToObject
+{
+    /// <summary>
+    /// 转换运算符
+    /// </summary>
+    public class ConvertTest 
+    {
+        [Fact]
+        public void Test()
+        {
+           var cc=  Enumerable.Empty<string>();
+        }
+    }
+}
diff --git a/LinqStudy.Test/LinqToObject/CreateTest.cs b/LinqStudy.Test/LinqToObject/CreateTest.cs
index 0aaacc5..407a8f0 100644
--- a/LinqStudy.Test/LinqToObject/CreateTest.cs
+++ b/LinqStudy.Test/LinqToObject/CreateTest.cs
@@ -1,4 +1,10 @@
 using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+
+using Xunit;
+using FluentAssertions;
 
 namespace LinqStudy.Test.LinqToObject
 {
@@ -7,5 +13,32 @@ namespace LinqStudy.Test.LinqToObject
     /// </summary>
     public class CreateTest
     {
+        /// <summary>
+        ///  Empty 返回指定类型的空集，没有任何元素的集合。
+        ///  Enumerable的静态方法，常用来做初始种子集合。
+        /// </summary>
+        /// <remarks>
+        ///  Enumerable
+        /// </remarks>
+        [Fact]
+        public void Empty_string_Test()
+        {
+           var ini= Enumerable.Empty<string>();
+
+           Assert.IsType<string[]>(ini);
+           Assert.Empty(ini);
+        }
+
+        /// <summary>
+        /// 注意：返回值为Enumerable<T>,而不是List<T> 
+        /// </summary>
+        [Fact]
+        public void Empty_Class_Test()
+        {
+            var ini = Enumerable.Empty<Person>();
+
+            Assert.IsType<Person[]>(ini);
+            Assert.Empty(ini);
+        }
     }
 }
diff --git a/LinqStudy.Test/Other/IndexersTest.cs b/LinqStudy.Test/Other/IndexersTest.cs
new file mode 100644
index 0000000..42e6e0b
--- /dev/null
+++ b/LinqStudy.Test/Other/IndexersTest.cs
@@ -0,0 +1,81 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+using Xunit;
+
+namespace LinqStudy.Test.Other
+{
+    /// <summary>
+    /// 索引器测试
+    /// </summary>
+    public class IndexersTest
+    {
+        [Fact]
+        public void Test()
+        {
+            PersonIndexers indexer = new PersonIndexers( PersonManager.GetPersons());
+
+            Assert.Equal(1, indexer[0].Id);
+        }
+    }
+
+    public class PersonIndexers
+    {
+        private List<Person> Persons=new List<Person>();
+
+        public PersonIndexers(List<Person> people)
+        {
+            Persons = people;
+        }
+
+        public Person this[int index]
+        {
+            get
+            {
+                if (index >= 0 && index < Persons.Count)
+                {
+                    return Persons[index];
+                }
+                else
+                {
+                    return null;
+                }
+            }
+            set {
+                if (index >= 0 && index < Persons.Count)
+                {
+                    Persons[index] = value;
+                }
+                else
+                {
+                     throw new IndexOutOfRangeException();
+                }
+            }
+        }
+    }
+
+    public class EmployeeIndexers 
+    {
+        private List<Employee> Employees;
+
+        public EmployeeIndexers(List<Employee> _employees)
+        {
+            Employees = _employees;
+        }
+
+        public Employee this[string name]
+        {
+            get
+            {
+                return Employees.Find(q => q.Name== name);
+            }
+            set
+            {
+                var idx= Employees.FindIndex(q => q.Id == value.Id);
+                Employees[idx] = value;
+            }
+        }
+        
+    }
+}
diff --git a/LinqStudy/IEnumerableDemo/Demo.cs b/LinqStudy/IEnumerableDemo/Demo.cs
new file mode 100644
index 0000000..6a95b97
--- /dev/null
+++ b/LinqStudy/IEnumerableDemo/Demo.cs
@@ -0,0 +1,108 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Text;
+
+namespace LinqStudy.IEnumerableDemo
+{
+    /// <summary>
+    /// 普通学生类
+    /// </summary>
+    public class Student
+    {
+        public string Name { get; set; }
+        public int Age { get; set; }
+    }
+
+    /// <summary>
+    /// 实现可枚举接口
+    /// </summary>
+    public class Students : IEnumerable
+    {
+        private Student[] arrStudent;
+
+        public Students(Student[] collection)
+        {
+            arrStudent = collection;
+        }
+
+        public Student this[int index]
+        {
+            get { return arrStudent[index]; }
+        }
+
+        public int Count
+        {
+            get { return arrStudent.Length; }
+        }
+
+        /// <summary>
+        /// 实现接口
+        /// </summary>
+        /// <returns></returns>
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return new StudentIterator(this);
+        }
+    }
+
+    /// <summary>
+    /// 实现枚举器接口
+    /// </summary>
+    public class StudentIterator : IEnumerator
+    {
+        private Students arrStudents;
+        private int idx;
+
+        internal StudentIterator(Students collection)
+        {
+            this.arrStudents = collection;
+            idx = -1;
+        }
+
+        object IEnumerator.Current
+        {
+            get { return arrStudents[idx]; }
+        }
+
+        public bool MoveNext()
+        {
+            idx++;
+            return idx < arrStudents.Count;
+        }
+
+        public void Reset()
+        {
+            idx = -1;
+        }
+        public void Dispose() { }
+    }
+
+    //使用
+    public class UseDemo
+    {
+        public void Test()
+        {
+            Students arrStudent = new Students
+            (
+                new Student[] 
+                {
+                    new Student() { Name = "张三", Age = 23 },
+                    new Student() { Name = "李四", Age = 24 },
+                    new Student() { Name = "王五", Age = 45 },
+                    new Student() { Name = "DDD", Age = 21 },
+                    new Student() { Name = "BBB", Age = 14 },
+                    new Student() { Name = "CCC", Age = 3 },
+                    new Student() { Name = "AAA", Age = 22 },
+                    new Student() { Name = "BBB", Age = 55 },
+                    new Student() { Name = "CCC", Age = 43 },
+                }
+            );
+
+            foreach (Student obj in arrStudent)
+            {
+                Console.WriteLine("姓名：" + obj.Name + ",年龄：" + obj.Age);
+            }
+        }
+    }
+}