沥青混合料中沥青用量可以采用( )来表示。 A．沥青含量 B．粉胶比 C．油石比

在网络层上实现网络互连的设备是（）。

A.路由器

B.交换机

C.集线器

D.中继器

（）是用于画眼影、腮红、轮廓红及掸浮粉的化妆用具。

A.粉底

B.蜜粉

C.口红

D.化妆刷

书法展示：请用手写印刷体抄写下面短文

Recently, recycling textbooks has been put into practice in some provinces. As far as I am concerned, it is a good way which will benefit both society and us students.

For one thing, it is good news to students from poor families who can’t afford textbooks. For another, recycling textbooks can save natural resources. We are cutting down too many trees every day. In the long run, it helps to develop the students’ environmental awareness. What’s more, students may learn to share and work with others through recycling textbooks.

To sum up, I consider recycling textbooks useful and helpful.

第(14)～(15)是基于下述描述：
设有图书管理数据库：
图书(总编号C(6)，分类号C(8)，书名C(16)，作者C(6)，出版单位C(20)，单价N(6,2))
读者(借书证号C(4)，单位C(8)，姓名C(6)，性别C(2)，职称C(6)，地址C(20))
借阅(借书证号C(4)，总编号C(6)，借书日期D(8))

对图书管理数据库，查询图书表中的所有元组。请对下面的SQL语句填空： 【14】