A、To examine the situation of lens. B、To regulate the focal distance. C、To position the desired photo within the camera’ s frame

Most of us still have lots of photographs sitting around from the days when we used cameras, not telephones, to take pictures. There are probably many photos stored away that we do not look at and may never see again. But these images, representing memories from our past, do not have to be lost. (19)Google has created a tool to help bring these forgotten pictures back to life in very high quality.
The recently-launched PhotoScan app works the same as an image scanner. But this software program uses the camera on your phone to capture images as digital copies. It is a quick and easy way to save old photos without having to spend money on new equipment. The PhotoScan app uses new technology to improve the capturing process. This makes it possible to take a picture of a photo with a camera phone, without glare, a common problem.
(20)After opening the app, the user first positions the desired photo within the camera’s frame. When this is done, (21)four small circles appear in different places over the photo. The user then moves the phone over each of the circles, which change color after the process is complete. And that’s it! The app finds the edges of the photo, straightens the image, and puts it in the right position while removing glare. From this point, the pictures can easily be saved to the Google Photos app or somewhere else. If you do have Google Photos, images are organized by face or place and can easily be searched. The release of PhotoScan came at the same time as some changes to the Google Photos app.
Questions 19 to 21 are based on the passage you have just heard.
19.What’s the purpose of PhotoScan app?
20.What’s the first step after opening the app?
21.How many circles appear in different places over the photo?