题目

下列关于①～⑨物质与结构在各种生物中存在的叙述，不正确的是（    ）     ①核酸  ②蛋白质  ③中心体  ④叶绿体  ⑤线粒体  ⑥核膜  ⑦核糖体  ⑧细胞膜 ⑨细胞壁     A．①、②在噬菌体、大肠杆菌、水绵、草履虫体内都存在        B．⑦、⑧、⑨在蓝藻和水绵体内都存在     C．①～⑨在菠菜叶肉细胞中都存在         D．⑥、⑧都具有选择透过性单词拼写。根据首字母和中文填空，请注意使用单词的适当形式。 1. They are my g______ (祖父母). They are very kind. 2. —How do you s______ (拼写) pen?   —P-E-N, pen. 3. I have two d_____ (字典) at home. I can look up new words in them. 4. Please a______ (回答) these questions in English. They aren't difficult. 5. Mum, I need some things for class. Can you b_____ (带来) them to school for me?