diff --git a/DbContext.md b/DbContext.md
index a84dfa1..3e8aada 100644
--- a/DbContext.md
+++ b/DbContext.md
@@ -250,6 +250,10 @@ uow.OnEntityChange = report => {
 public class ChangeInfo {
   public object Object { get; set; }
   public EntityChangeType Type { get; set; }
+  /// <summary>
+  /// Type = Update 的时候，获取更新之前的对象
+  /// </summary>
+  public object BeforeObject { get; set; }
 }
 public enum EntityChangeType { Insert, Update, Delete, SqlRaw }
 ```
diff --git a/工作单元.md b/工作单元.md
index e27e613..e6bb7d5 100644
--- a/工作单元.md
+++ b/工作单元.md
@@ -1,14 +1,13 @@
-
 UnitOfWork 可将多个仓储放在一个单元管理执行，最终通用 Commit 执行所有操作，内部采用了数据库事务；
 
 ```csharp
 var connstr = "Data Source=127.0.0.1;Port=3306;User ID=root;Password=root;" + 
-    "Initial Catalog=cccddd;Charset=utf8;SslMode=none;Max pool size=10";
+  "Initial Catalog=cccddd;Charset=utf8;SslMode=none;Max pool size=10";
 
 static IFreeSql fsql = new FreeSql.FreeSqlBuilder()
-    .UseConnectionString(FreeSql.DataType.MySql, connstr)
-    .UseAutoSyncStructure(true) //自动同步实体结构到数据库
-    .Build(); //请务必定义成 Singleton 单例模式
+  .UseConnectionString(FreeSql.DataType.MySql, connstr)
+  .UseAutoSyncStructure(true) //自动同步实体结构到数据库
+  .Build(); //请务必定义成 Singleton 单例模式
 ```
 
 ## 如何使用
@@ -36,36 +35,36 @@ uow.GetOrBeginTransaction() 方法可获取事务对象。
 ```csharp
 public interface IUnitOfWork : IDisposable {
 
-    DbTransaction GetOrBeginTransaction(bool isCreate = true);
+  DbTransaction GetOrBeginTransaction(bool isCreate = true);
 
-    IsolationLevel? IsolationLevel { get; set; }
+  IsolationLevel? IsolationLevel { get; set; }
 
-    /// <summary>
-    /// 是否启用工作单元
-    /// </summary>
-    bool Enable { get; }
+  /// <summary>
+  /// 是否启用工作单元
+  /// </summary>
+  bool Enable { get; }
 
-    void Commit();
+  void Commit();
 
-    void Rollback();
+  void Rollback();
 
-    /// <summary>
-    /// 禁用工作单元
-    /// <exception cref="Exception"></exception>
-    /// <para></para>
-    /// 若已开启事务（已有Insert/Update/Delete操作），调用此方法将发生异常，建议在执行逻辑前调用
-    /// </summary>
-    void Close();
+  /// <summary>
+  /// 禁用工作单元
+  /// <exception cref="Exception"></exception>
+  /// <para></para>
+  /// 若已开启事务（已有Insert/Update/Delete操作），调用此方法将发生异常，建议在执行逻辑前调用
+  /// </summary>
+  void Close();
 
-    /// <summary>
-    /// 开启工作单元
-    /// </summary>
-    void Open();
+  /// <summary>
+  /// 开启工作单元
+  /// </summary>
+  void Open();
 
-    /// <summary>
-    /// 此工作单元内的实体变化跟踪
-    /// </summary>
-    DbContext.EntityChangeReport EntityChangeReport { get; }
+  /// <summary>
+  /// 此工作单元内的实体变化跟踪
+  /// </summary>
+  DbContext.EntityChangeReport EntityChangeReport { get; }
 }
 ```
 
@@ -75,9 +74,9 @@ public interface IUnitOfWork : IDisposable {
 
 ```csharp
 fsql.SetDbContextOptions(opt => {
-    opt.OnEntityChange = report => {
-        Console.WriteLine(report);
-    };
+  opt.OnEntityChange = report => {
+    Console.WriteLine(report);
+  };
 });
 ```
 
@@ -86,7 +85,7 @@ fsql.SetDbContextOptions(opt => {
 ```csharp
 var uow = fsql.CreateUnitOfWork();
 uow.OnEntityChange = report => {
-    Console.WriteLine(report);
+  Console.WriteLine(report);
 };
 ```
 
@@ -94,8 +93,12 @@ uow.OnEntityChange = report => {
 
 ```csharp
 public class ChangeInfo {
-    public object Object { get; set; }
-    public EntityChangeType Type { get; set; }
+  public object Object { get; set; }
+  public EntityChangeType Type { get; set; }
+  /// <summary>
+  /// Type = Update 的时候，获取更新之前的对象
+  /// </summary>
+  public object BeforeObject { get; set; }
 }
 public enum EntityChangeType { Insert, Update, Delete, SqlRaw }
 ```