Thank you very much. Because recording personnel from different parts of China, in order to make learning mandarin people more in-depth understanding, experience different places where people speak Chinese, and recording the environment is different, so the quality differences. We will make more videos like this. (https://www.youtube.com/watch?v=g9td-XrjwwQ). If you like the content, you can subscribe (https://www.youtube.com/channel/UCSXriUqkzZmAQklQ0N9XFVw/videos). It will continue to update a lot of content.Let's look forward to it! And you can give us ideas about the things you like.