通篇时态不一致,改为一般过去时,对应下文
Mark （was） a middle school student.He （lived） in the middle of the town.About a mile from Mark's building,there （were要用there be句式,一般过去时） many old houses.They （were） all empty and going to be （pull被动要用过去分词） down.His father （said） they （were） dangerous and （told） him to keep away from them.But he （enjoyed） playing there very much.One Friday on their way home from school,Mark went into one of the empty old houses.He saw a door leading（to通向） a small dark room.He went into the room to see what he could find （这里去掉them,what充当从句的宾语）.Just then he heard a terrible sound.The roof of the old house fell off.Mark tired to open the door.However,he couldn't.(So表结果) he had to stay there.Mark was saved three days （later表后来,late是迟的） by some （policemen用复数）.They used dogs to find him.