【正确答案】
(Student's sample)
I have always considered college life is easy and colorful. But the idea disappeared when I go to college. College teachers are normal and they can not well teach us. So I am absent from class, I decide to learn by myself. I work very very hard and I have a dream to be the best student. When I graduate from college, my teacher said to me you are the best student.
(Improved sample)
I had thought that college life was easy and colorful. But when I went to college, I found I was wrong. College teachers were far from experts as I had expected and some even could not teach us well. So I began to be absent from class and decided to learn by myself instead. I worked very hard in the hope of being the best student. Finally, my dream came true when my teachers told me I was the top student upon my graduation.