一个细胞的细胞核中有20条染色体,连续四次有丝分裂后,产生的子细胞中染色体数是[ ]
A.10
B.20
C.30
D.40
答案:B
I think _______ is good for your health.
A.getting up late
B.drink more milk
C.eating more fruits
D.to eat more meat
对下游承担防洪任务的水库,以安全方式调度时就是控制出库流量为安全泄量进行调度。()