—What were you doing at this time yesterday?    

—I _____ basketball with my friends.     [ ]

A. was playing

B. had played

C. have played

D. played

临床上进行试验性治疗必须具备的条件包括（）

A.目前现有疗法无效

B.只有采取某种（些）新疗法才能挽救生命

C.征得患者或家属充分理解

D.受试者或相应法定监护人同意

E.医院伦理委员会或医院领导批准