题目

At the beginning of this term, my PE teacher suggested to me that I should take part in the marathon(马拉松). I was very surprised because I was ____ a good runner. In order to encourage me, he said that if I took part in the race, I would get the highest mark for the term's PE class. Therefore, I decided to have a ____ because I had nothing to lose.I prepared for the race very ____. I ran every day in the morning before school. And after school, I practiced running with many other runners on the sports ground. I even had the ____ diet for athletes. I heard that the special diet could ___ m北美洲地势的特点是（ ）A. 东高西低 B. 东西高，中部低C. 中部高，西部低 D. 四周高，中部低