-- Have you sent him a birthday present?
-- . I gave it to him two days ago
A:No, I haven't
B:Yes, I have
C:No, I'm not
D:Yes, I am
京杭运河北起____市,南至____省的____市。
细胞分裂通常是一个细胞分裂成两个细胞的过程.1个细胞经过4次分裂后的数目是( )