I could see a whale ________ by a pack of about six other killers.    [ ]

A. having been attacked        

B. being attacked    

C. to be attacked              

D. be attacked

红细胞吸收无机盐和葡萄糖的共同特点是（）

A.都可以从低浓度一侧到高浓度一侧

B.都需要供给ATP

C.都需要载体协助

D.既需要载体协助又需要消耗能量