—Hi，Mary.Would you like to go to the concert this evening?

—Sorry，Tom.________ tomorrow's lessons，I have no time to go out with you.

A．Not preparing

B．Not having prepared

C．Not to prepare

D．Being not prepared

诊断视神经胶质瘤，下列检查方法中最佳的是（）

A.平片

B.CT平扫

C.CT增强扫描

D.MRI

E.B超