—Have you ever been to Shanghai, Mary?          

—Yes, I _____ there for three days with my parents last month.             [ ]

A. have gone                

B. have been            

C. went                      

D. was

下列哪些属于烧伤的治疗原则()

A．保护烧伤区，防止和清除外源性污染

B．预防和治疗低血容量性休克

C．防治局部及全身性感染

D．促进创面愈合．减少疤痕形成及功能障碍

E．防治器官的并发症