【正确答案】I don't quite understand what it is like to know the deep mind of the friends by the eye, say, the window of the heart. I only can "see" the shape of the face by the fingertip. I can notice the happiness, sorrow and many other obvious emotions. By the feeling of touching their faces, I can recognize them, but I am not able to describe their exact expressions by touching. Of course, by other means, such as by the ideas they express, by whatever behaviors they show, I can also get to know their characters. But I was deprived of the possibility of further understanding of them, because, I believe that, to reach the further understanding, I need to see them with my own eyes and observe their reactions to various ideas and situations.