Come Back Soon

 My brother studies in a high school everyday until late. He is serious, I am proud of him.
 But, he lacks common sense. He made an unbelievable mistake last wednesday.
 In that morning, he said that ''I will come back at 6:30 p.m.'', and went to school. I approved of it and waited for him. However, he didn't come home at all till 8:30. Although I called his teacher, I wasn't able to know where he was.
 ''He may have an accident. I have to seek him?'' I thought. At that time, my brother went home and said ''I'm home!''
 I asked what he do until now. He calmly answered ''I changed my schedule and studied in a library.'' I was very amazed and blamed him. I think, we should tell the urgent change of schedule.