Alex Smith,a fifteen-year-old boy,studied in an American boarding school(寄宿学校).In this school,students could go into town after school in the afternoon.___1___ One afternoon,Alex walked to the town.He looked about at the shops and then went to a cinema.___2___ It was eight o’clock.He was a little worried.He walked back to the school as fast as possible.When he arrived,he ran quickly to the main entrance(人口).It was locked.He looked up at the window of his dormitory.It was on the third floor.The window was open.___3___ But the door was also locked.Then he saw another open window on the first floor.It was the window of the teachers' office.___4___ Alex quickly climbed into the room.Just then,he heard someone opened the door.He had to hide under the sofa at once.one minute later,a teacher came in.___5___ Under the sofa Alex had to lie on the floor.