患者，女性，23岁，L6磨牙银汞充填1周后自述咬物时疼痛，检查：见口腔卫生较好，无牙龈炎症，充填物表面有亮点，叩痛（+），无冷热刺激痛，处理时首选（）

A.调磨牙尖

B.调磨充填体

C.牙髓治疗

D.重新充填

E.全冠修复

_____ a teacher, John thinks that his main duty is to help the students become better learners.[ ]

A. As          

B. By            

C. About        

D. With