There ________ a pen and two books on the desk.[ ]
A. is
B. are
C. was
D. were
答案:A
需要加入适当的氧化剂才能实现的反应
A.PCl3→PCl5
B.MnO4-→Mn2+
C.SO3→SO42-
D.CO2→CO32-
本病例若需加止血药物,下列哪组最宜
A.乌梅、黄芪、党参
B.紫草、大黄、三七
C.山萸肉、煅龙牡、三七
D.郁金、三七、花蕊石
E.蛤粉炒阿胶、仙鹤草、白茅根