diff --git a/DrissionPage/chromium_base.py b/DrissionPage/chromium_base.py
index 23d3dc7..46429a8 100644
--- a/DrissionPage/chromium_base.py
+++ b/DrissionPage/chromium_base.py
@@ -116,16 +116,14 @@ class ChromiumBase(BasePage):
         return False
 
     def _onFrameStartedLoading(self, **kwargs):
-        """页面跳转时触发"""
-        # print('FrameStartedLoading')
+        """页面开始加载时触发"""
         if kwargs['frameId'] == self.tab_id:
             self._is_loading = True
             if self._debug:
                 print('FrameStartedLoading')
 
     def _onFrameStoppedLoading(self, **kwargs):
-        """页面跳转时触发"""
-        # print('FrameStoppedLoading')
+        """页面加载完成后触发"""
         if kwargs['frameId'] == self.tab_id and self._first_run is False and self._is_loading:
             if self._debug:
                 print('FrameStoppedLoading')
diff --git a/DrissionPage/chromium_element.py b/DrissionPage/chromium_element.py
index 703659e..e2066c9 100644
--- a/DrissionPage/chromium_element.py
+++ b/DrissionPage/chromium_element.py
@@ -32,7 +32,7 @@ class ChromiumElement(DrissionElement):
         self._scroll = None
         self._tag = None
         if not node_id and not obj_id:
-            raise TypeError('node_id或obj_id必须传入一个。')
+            raise RuntimeError('元素可能已失效。')
 
         if node_id:
             self._node_id = node_id
diff --git a/DrissionPage/session_page.py b/DrissionPage/session_page.py
index ce9ac6f..b4ad6f8 100644
--- a/DrissionPage/session_page.py
+++ b/DrissionPage/session_page.py
@@ -194,6 +194,7 @@ class SessionPage(BasePage):
 
     @property
     def download(self) -> DownloadKit:
+        """返回下载器对象"""
         if not hasattr(self, '_download_kit'):
             self._download_kit = DownloadKit(session=self)
 
diff --git a/DrissionPage/web_page.py b/DrissionPage/web_page.py
index d3b2c3c..0244d0c 100644
--- a/DrissionPage/web_page.py
+++ b/DrissionPage/web_page.py
@@ -383,6 +383,7 @@ class WebPage(SessionPage, ChromiumPage, BasePage):
 
     @property
     def download(self) -> DownloadKit:
+        """返回下载器对象"""
         if self.mode == 'd':
             self.cookies_to_session()
         return super().download