— _______ is it from your home to your school, Anna?
— It's quite near, only five minutes' walk.
A:How many
B:How far
C:How long
D:How soon
秋水仙素可诱导多倍体,它作用于细胞分裂的
X
1
2
3
P
P1
P2
P3
则EX=2的充要条件是( )