The secretary worked late into night, _____ a long speech for the president. [ ]

A. to prepare

B. preparing

C. prepared

D. was preparing

茎方柱形，表面紫棕色或淡绿色，叶片宽披针形或卵形，味辛凉。此药材是（）

A.荆芥

B.半枝莲

C.益母草

D.穿心莲

E.薄荷