diff --git a/problem/views.py b/problem/views.py
index 1d1702d..e7c7e1d 100644
--- a/problem/views.py
+++ b/problem/views.py
@@ -122,7 +122,7 @@ class ProblemAdminAPIView(APIView):
                 return success_response(ProblemSerializer(problem).data)
             except Problem.DoesNotExist:
                 return error_response(u"题目不存在")
-        problem = Problem.objects.all().order_by("-last_update_time")
+        problem = Problem.objects.all().order_by("-create_time")
         visible = request.GET.get("visible", None)
         if visible:
             problem = problem.filter(visible=(visible == "true"))
diff --git a/static/src/js/app/admin/problem/add_problem.js b/static/src/js/app/admin/problem/add_problem.js
index e8b7bba..7331a8a 100644
--- a/static/src/js/app/admin/problem/add_problem.js
+++ b/static/src/js/app/admin/problem/add_problem.js
@@ -13,6 +13,10 @@ require(["jquery", "avalon", "editor", "uploader", "bsAlert", "csrfToken", "tagE
                             bsAlert("题目描述不能为空!");
                             return false;
                         }
+                        if (vm.timeLimit < 1000 || vm.timeLimit > 5000) {
+                            bsAlert("保证时间限制是一个1000-5000的合法整数");
+                            return false;
+                        }
                         if (vm.samples.length == 0) {
                             bsAlert("请至少添加一组样例!");
                             return false;
diff --git a/static/src/js/app/admin/problem/edit_problem.js b/static/src/js/app/admin/problem/edit_problem.js
index c64d64c..defb64e 100644
--- a/static/src/js/app/admin/problem/edit_problem.js
+++ b/static/src/js/app/admin/problem/edit_problem.js
@@ -15,6 +15,10 @@ require(["jquery", "avalon", "editor", "uploader", "bsAlert", "csrfToken", "tagE
                             bsAlert("题目描述不能为空!");
                             return false;
                         }
+                        if (vm.timeLimit < 1000 || vm.timeLimit > 5000) {
+                            bsAlert("保证时间限制是一个1000-5000的合法整数");
+                            return false;
+                        }
                         if (vm.samples.length == 0) {
                             bsAlert("请至少添加一组样例!");
                             return false;
diff --git a/template/admin/announcement/announcement.html b/template/admin/announcement/announcement.html
index 03f110f..5c0d4d9 100644
--- a/template/admin/announcement/announcement.html
+++ b/template/admin/announcement/announcement.html
@@ -56,7 +56,7 @@
         <div class="form-group">
             <label>标题</label>
             <input name="title" type="text" class="form-control" id="title" placeholder="公告标题"
-                   data-error="请填写公告标题" maxlength="50" required>
+                   data-error="请填写公告标题(标题不得超过50字)" maxlength="50" required>
             <div class="help-block with-errors"></div>
         </div>
         <div class="form-group">
diff --git a/template/admin/group/group_detail.html b/template/admin/group/group_detail.html
index 525d7bc..208aa71 100644
--- a/template/admin/group/group_detail.html
+++ b/template/admin/group/group_detail.html
@@ -31,7 +31,7 @@
         <div class="col-md-12">
             <div class="form-group"><label>小组名</label>
                 <input type="text" name="name" class="form-control" ms-duplex="name"
-                        data-error="请填写小组名" maxlength="20" required>
+                        data-error="请填写小组名(名称不能超过20字)" maxlength="20" required>
                 <div class="help-block with-errors"></div>
             </div>
         </div>
diff --git a/template/admin/problem/add_problem.html b/template/admin/problem/add_problem.html
index 04d126b..fadea4c 100644
--- a/template/admin/problem/add_problem.html
+++ b/template/admin/problem/add_problem.html
@@ -4,7 +4,7 @@
         <div class="form-group col-md-12">
             <label>题目标题</label>
             <input type="text" name="title" autofocus class="form-control" ms-duplex="title"
-                   data-error="请填写题目名称(名称不能超过30个字)" maxlength="30" required>
+                   data-error="请填写题目名称(名称不能超过50个字)" maxlength="50" required>
             <div class="help-block with-errors"></div>
         </div>
 
@@ -18,7 +18,7 @@
         <div class="col-md-3">
             <div class="form-group"><label>时间限制(ms)</label>
                 <input type="number" name="timeLimit" class="form-control" ms-duplex="timeLimit"
-                       data-error="请输入时间限制(保证是一个1-5000的合法整数)" maxlength="5000" required>
+                       data-error="请输入时间限制(保证是一个1000-5000的合法整数)" required>
                 <div class="help-block with-errors"></div>
             </div>
         </div>
diff --git a/template/admin/problem/edit_problem.html b/template/admin/problem/edit_problem.html
index 2b63b2c..cdee4a0 100644
--- a/template/admin/problem/edit_problem.html
+++ b/template/admin/problem/edit_problem.html
@@ -18,7 +18,7 @@
         <div class="col-md-3">
             <div class="form-group"><label>时间限制(ms)</label>
                 <input type="number" name="timeLimit" class="form-control" ms-duplex="timeLimit"
-                       data-error="请输入时间限制(保证是一个1-5000的合法整数)" maxlength="5000" required>
+                       data-error="请输入时间限制(保证是一个1000-5000的合法整数)" required>
                 <div class="help-block with-errors"></div>
             </div>
         </div>
diff --git a/template/admin/user/user_list.html b/template/admin/user/user_list.html
index f884efc..8e8c0f4 100644
--- a/template/admin/user/user_list.html
+++ b/template/admin/user/user_list.html
@@ -70,7 +70,7 @@
                 </div>
                 <div class="form-group col-md-4"><label>电子邮箱</label>
                     <input name="email" type="email" class="form-control" ms-duplex="email"
-                           data-error="请填写邮箱地址" required>
+                           data-error="请填写邮箱地址(并保证是正确的邮箱格式)" required>
                     <div class="help-block with-errors"></div>
                 </div>
                 <div class="form-group col-md-4"><label>用户类型</label>