2009年1月1日起，青岛市新购公务车要首选“环保型”，这体现了青岛市政府保护环境，与自然和谐相处的执政理念。[ ]

______his arrival at the classroom on his first day at school, the teacher _______. [ ]

A. At; was played a trick on                  

B. On; played a trick at his students

C. To; played a trick on his students            

D. On; was played a trick on