You used to be really little fat, _______ you? [ ]
A. did
B. Didn't
C. didn't
D. Did
答案:C
回转式进料装置的工作过程是怎样的?
甲型流感病毒抗原小幅度变异称为()
A.溶原性转换
B.抗原性转换
C.抗原性漂移
D.H-O变异
E.W-V变异