Read and complete. 再读短文,完成下面的概要。(下划线部分为教材中需要修改部分) When I was a boy, I used to go camping with my classmates and teachers every summer. Once we were camping in a place above a river. If someone wanted to reach the river, he had to walk past our camp. Several days later, the teacher had to be away for a day. That afternoon, we had supper early. While we were eating and talking, we saw a man walking past and going down towards the river. We all felt that this man looked very strange, but because each of us was afraid of looking stupid, no one said anything. When we had to wash the plates after supper, no one moved towards the river — we stood looking at each other ashamed. Then we all shouted at once and began talking about the strange man who had walked past us. We knew that he could only return by passing through our camp. Then one of the boys suggested we should go and see what the man was doing. Moving very slowly, we crept down towards the bank. To our surprise, there was no one on the bank. Feeling surprised, we went back to our camp. We told the teacher what had happened in the evening. Smiling, he doubted that we had seen the man. Many years have passed, but I still wondered what I saw that day.