Some of these videos might be a bit long since it will be a whole module in each video so please feel free to make use of the time stamps in descriptions if you're looking for specific topics only or just want to refresh on certain topics only.
有些视频可能会有点长，因为每个视频都是一个完整的模块，所以如果你只想寻找特定的主题或只想复习特定的主题，请使用描述中的时间戳。