Studying English lies not so much in ________we learn by heart as in ________ we really understand. [      ]

A. that; what     

B. what; what

C. that; that         

D. what; that

苯妥英钠治疗洋地黄中毒所致室上性心动过速，急用时可静脉推注（）

A.100mg/5～10min

B.50mg/5～10min

C.150mg/5～10min

D.200mg/5～10min

E.250mg/5～10min