枝条都由____发育成的．
The computer company just released an ____ (更新) version last week, and it'll be used in over 50 local classrooms this coming school year.
请在下列各序号后面的横线上填上恰当的结构名称，以完善细胞的概念图．
①____②____③____④____⑤____．
与发展中国家相比，发达国家具有的特征是( ）
