A:76%
B:5%
C:19%
D:38%
与精子的形成相比,卵细胞的形成过程中不会出现的是( )
He was ____ (interest) in science when he was ten years old.
已知正方体ABCD-A1B1C1D1的棱长为a,AM→=12MC1→,点N为B1B→的中点, 则MN=( )