Having missed lessons for a week, I needed a written excuse.Not knowing his name, I found it diffcult to introdue him.Stuck in the mud, the car had to be pushed--(no revision neded)Walking down the street, they suddenly had a car stopped beside them.Seeing from the top of the mountain, I thought the lake looked very beautiful..几个问题.首先我不知道应该改成什么句式,什么部分需要保留,什么可以添加（比如说1,2,3,6我都添加了主语）.其次,这些东西学通了很有益,楼主你如果打算在美国接受高等教育,赛达那一关迟早得过.