It is not enough only_______the rules of grammar if you want to learn English well.

A．keeping in the mind

B．to keep in mind

C．to keep in your mind

D．keeping in your mind

从病理生理研究得出，脊髓损伤的最佳治疗时间是伤后（）

A.1h

B.6h

C.24h

D.2d

E.6d