题目

听第二段对话，回答小题。 （1） Where are the two speakers? A . At school. B . At home. C . In the lost and found office. （2） What color is the boy's pencil case? A . Red. B . Yellow. C . Green. （3） Where is Tina's English book? A . In her backpack. B . In the boy's backpack. C . In the bookcase. 答案：B C B 下列是由双层磷脂分子作为基本骨架的膜结构是 [　　] A．病毒的囊膜 B．细菌的荚膜 C．小肠的粘膜 D．叶绿体外膜