Put the following confused sentences in order.

(1) We lined up and walked to the front of the exhibition hall.

(2) Looking back, there was a long queue near the gate, and there were still many people waiting in line in front of the gate of the exhibition hall.

(3) Everyone enters the door under the guidance of the instructor (progress room)

(4) At the entrance of the exhibition room, a big placard with a preface is erected.

(5) The first exhibition hall shows the technological development of China's aerospace industry.

(6) There are many pictures and objects in several exhibition rooms (in the middle), and there are explanatory words under each picture.

(7) The conclusion of the exhibition room (at the exit) contains two words that some of our classmates said they had not learned.

We walked out of the exhibition hall from the exit in turn.