diff --git a/app/Http/Controllers/CategoriesController.php b/app/Http/Controllers/CategoriesController.php
index 2529540..861894c 100644
--- a/app/Http/Controllers/CategoriesController.php
+++ b/app/Http/Controllers/CategoriesController.php
@@ -4,12 +4,13 @@ namespace App\Http\Controllers;
 
 use App\Models\Category;
 use App\Models\Topic;
+use Illuminate\Http\Request;
 
 class CategoriesController extends Controller
 {
-    public function show(Category $category)
+    public function show(Category $category, Request $request)
     {
-        $topics = Topic::where('category_id', $category->id)->with('user', 'category')->paginate();
+        $topics = Topic::where('category_id', $category->id)->withOrder($request->order)->with('user', 'category')->paginate();
         return view('topics.index', compact('topics', 'category'));
     }
 }
diff --git a/app/Http/Controllers/TopicsController.php b/app/Http/Controllers/TopicsController.php
index 6880c76..f462cbf 100644
--- a/app/Http/Controllers/TopicsController.php
+++ b/app/Http/Controllers/TopicsController.php
@@ -4,6 +4,7 @@ namespace App\Http\Controllers;
 
 use App\Http\Requests\TopicRequest;
 use App\Models\Topic;
+use Illuminate\Http\Request;
 
 class TopicsController extends Controller
 {
@@ -12,9 +13,9 @@ class TopicsController extends Controller
         $this->middleware('auth', ['except' => ['index', 'show']]);
     }
 
-    public function index()
+    public function index(Request $request, Topic $topic)
     {
-        $topics = Topic::with('user', 'category')->paginate();
+        $topics = $topic->with('user', 'category')->withOrder($request->order)->paginate();
         return view('topics.index', compact('topics'));
     }
 
diff --git a/app/Models/Category.php b/app/Models/Category.php
index 07a5f91..d3a4c95 100644
--- a/app/Models/Category.php
+++ b/app/Models/Category.php
@@ -2,7 +2,7 @@
 
 namespace App\Models;
 
-class Category extends BaseModel
+class Category extends Model
 {
     protected $guarded = ['id'];
 
diff --git a/app/Models/Topic.php b/app/Models/Topic.php
index f6b20e2..a675a31 100644
--- a/app/Models/Topic.php
+++ b/app/Models/Topic.php
@@ -7,6 +7,35 @@ class Topic extends Model
     protected $fillable = ['"title', 'body', 'user_id', 'category_id', 'reply_count', 'view_count', 'last_reply_user_id', 'order', 'excerpt', 'slug'];
 
 
+    public function scopeWithOrder($query, $order)
+    {
+        // 不同的排序，使用不同的数据读取逻辑
+        switch ($order) {
+            case 'recent':
+                $query = $this->recent();
+                break;
+
+            default:
+                $query = $this->recentReplied();
+                break;
+        }
+        // 预加载防止 N+1 问题
+        return $query->with('user', 'category');
+    }
+
+    public function scopeRecentReplied($query)
+    {
+        // 当话题有新回复时，我们将编写逻辑来更新话题模型的 reply_count 属性，
+        // 此时会自动触发框架对数据模型 updated_at 时间戳的更新
+        return $query->orderBy('updated_at', 'desc');
+    }
+
+    public function scopeRecent($query)
+    {
+        // 按照创建时间排序
+        return $query->orderBy('created_at', 'desc');
+    }
+
     public function user()
     {
         return $this->belongsTo(User::class);
diff --git a/resources/views/topics/index.blade.php b/resources/views/topics/index.blade.php
index 747b6b1..fc1ec66 100644
--- a/resources/views/topics/index.blade.php
+++ b/resources/views/topics/index.blade.php
@@ -16,8 +16,10 @@
 
                 <div class="panel-heading">
                     <ul class="nav nav-pills">
-                        <li role="presentation" class="active"><a href="#">最后回复</a></li>
-                        <li role="presentation"><a href="#">最新发布</a></li>
+                        <li role="presentation" class="{{active_class(!if_query('order','recent'))}}"><a
+                                    href="{{Request::url()}}?order=default">最后回复</a></li>
+                        <li role="presentation" class="{{active_class(if_query('order','recent'))}}"><a
+                                    href="{{Request::url()}}?order=recent">最新发布</a></li>
                     </ul>
                 </div>