请按顺序参考上边图片，生成讲解视频，要求语言通俗易懂，深入浅出，适合七年级学生接受---I apologize, but the image you provided is completely dark blue and appears to be blank. There is no discernible text, charts, or any other content to extract. Please ensure you upload an image that contains the content you wish to have extracted. I apologize, but the image you provided is completely dark blue and appears to be blank. There is no discernible text, charts, or any other content to extract. Please ensure you upload an image that contains the content you wish to have extracted. I apologize, but the image you provided is completely dark blue and appears to be blank. There is no discernible text, charts, or any other content to extract. Please ensure you upload an image that contains the content you wish to have extracted. I apologize, but the image you provided is completely dark blue and appears to be blank. There is no discernible text, charts, or any other content to extract. Please ensure you upload an image that contains the content you wish to have extracted. I apologize, but the image you provided is completely dark blue and appears to be blank. There is no discernible text, charts, or any other content to extract. Please ensure you upload an image that contains the content you wish to have extracted. I apologize, but the image you provided is completely dark blue and appears to be blank. There is no discernible text, charts, or any other content to extract. Please ensure you upload an image that contains the content you wish to have extracted.