药物临床研究被批准后应当实施期限为

A．新药申请
B．已有国家标准药品的申请
C．进口药品申请
D．补充申请
E．临床研究申请

He asked ____ for the violin. [ ]

A. did I pay how much

B. I paid how much

C. how much I paid

D. how much did I pay