A:核酸组成单位种类相同
B:组成元素的种类相同
C:都具有蛋白质和核酸
D:都含有磷脂双分子层
Cairo is one of the biggest and busiest ____ (city) in Egypt.
As the smallest child of his family, Alex is always longing for the time _______ he should be able to be independent.
左图为“北京市简图”,右图为“北京城市功能空间布局示意图”。读图完成下列各题。
6+(12÷4)=____。