A:CaCl2
B:CO2
C:H2O
D:Na2O2
_______he had failed many times, he didn't give up and succeeded in the end.
①L期有8条染色体 ②P期紧接在L期之后
③P期与M期细胞内核DNA数相等 ④P期有8条染色单体.
一个细胞进行3次分裂,形成几个细胞?( )
读“京津冀地区和长江三角洲地区示意图”,回答下列问题。