On hearing the bell students ran into the classroom as quickly as they could. But a boy ,LIMing , whose father died a month ago , was late for the class. He stood outside the classroom silently . I smiled to him and let him come in. After a while ,he cried on his desk . Then I walked to him and asked what had happened . He told me that his mother was ill and he had to take some medicine for her . At the same time ,he apologized to me for his lateness . Moved by his words , I praised him for his deeds and decided to sing a song named "mother" for the students . How time flies ! Class was over before I realized it .