题目

下列各项中，具有双层膜结构的是 ①叶绿体 ②线粒体 ③内质网 ④高尔基体  ⑤核膜 ⑥液泡 A．①②③         B．①②⑤         C．①②⑥         D．①②④ 答案：B写作。你能仿照本单元所学知识，描述一下怎样装饰圣诞树吗？写一写。                                           How to put up a Christmas Tree?   ____________________________________________________________________________________   ____________________________________________________________________________________   ____________________________________________________________________________________   ____________________________________________________________________________________   ____________________________________________________________________________________