强心苷元是甾体母核C-17侧链为不饱和内酯环，甲型强心苷元17位侧链为( )

A．六元不饱和内酯环
B．五元不饱和内酯环
C．五元饱和内酯环
D．六元饱和内酯环
E．七元不饱和内酯环

--- Kathy, you’ve got a chance to deliver a speech at the conference?

--- Yes, but how could I ______ the meeting date fixed so soon?. [ ]

A. while

B. as

C. after

D. with