________well prepared you are,you still need a lot of    luck in mountain climbing.    [ ]

A. However    

B. Whatever    

C. No matter    

D. Although

治疗恶性贫血时，宜选用（）

A.口服维生素B₁₂

B.肌注维生素B₁₂

C.口服硫磺酸亚铁

D.肌注右旋糖酐铁

E.肌注叶酸