Last week, it was on duty  our class was in cafeteria for self-management. On the first day, I      (shock) to see so much leftover food thrown away by students. What a waste! Concerned about it, my classmates and I had a    discussion on how      (solve) the problem.  Lots of good ideas came up, such as holding class meetings, putting up wall newspapers and charging a fine for wasting food. Finally we all agreed that wall newspapers would be      (good ) choice.
The next day, we put our idea into reality. Towards lunch time, we put up a wall newspaper outside the school cafeteria,      (call) on students not to waste food. Many students gathered around to read and expressed their support. To my great delight, there were changes soon. In the cafeteria, I found the trays    (return) after lunch all empty   any leftover. Food was saved and the dining hall was cleaner.    ( see )this, I felt relieved and took pride in     we had done.