It depends. If the ppt page is dominated by pictures, it will be quick, that is, it will be easy to take. If it is mainly text, it will be slower. Generally speaking, it takes 20 minutes to talk about 10 pages in one minute, and it only takes 10 minutes to talk about 20 pages in one minute. This can also be played by yourself according to the listed topics and the content to be explained. As for time, it depends on the importance of the content and the space for your own play, and you can explain what you want to express.