— You look so young. Haven't you graduated from your university?

— Yes. I _____ in the English department of Yunnan University for four years. [ ]

A. had studied

B. has studied

C. studied

D. was studying

成釉细胞瘤有以下临床表现，但不包括

A．男性患者占绝大多数

B．渐进性颌骨膨大

C．按之有乒乓感

D．X线可为单囊或多囊性透射影

E．肿瘤区牙齿移位、松动