制备缓释制剂时，加入阻滞剂的目的是（）
A.促进药物吸收
B.延缓药物释放
C.增加片剂硬度
D.使制剂更稳定
E.定位释放药物
参考答案：B
John received an invitation to dinner, and with his work ____, he gladly accepted it. [ ]
A. finished
B. finishing
C. having finished
D. was finished
运用内插法近似计算IRR时，为缩小误差，两个临近值NPVm和NPVn所对应的折现率 rm与rn之差不得大于( )。
A．1%
B．2%
C．5%
D．7%
