We lined up neatly and walked to the gate of the exhibition hall. A large placard was erected at the entrance of the exhibition room. Sorting question

(7) Looking back, I saw that there were still many people queuing up in front of the exhibition hall gate, waiting to enter.

(2) There is a large placard at the entrance of the exhibition room with "Foreword" written on it.

(1) We walked in a neat queue to the gate of the exhibition hall.

(5) There are many pictures and objects in several exhibition rooms in the middle.

(4) The first exhibition room shows the development of my country's aerospace industry.

(3) Everyone enters the exhibition room under the guidance of the instructor.

(6) We walked out of the exhibition hall from the exit one after another.