问题 单项选择题

第(33)~(35)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))

对于图书管理数据库,检索借阅了《现代网络技术基础》一书的借书证号。下面SQL语句正确的是______。 SELECT借书证号FROM借阅WHERE总编号=;

A.(SELECT借书证号FROM图书WHERE书名="现代网络技术基础")

B.(SELECT总编号FROM图书WHERE书名="现代网络技术基础")

C.(SELECT借书证号FROM借阅WHERE书名="现代网络技术基础")

D.(SELECT总编号FROM借阅WHERE书名="现代网络技术基础")

答案

参考答案:B

解析:[知识点] SQL的数据查询功能/嵌套查询[评析] 本题是嵌套查询,内层查询完成的是对图书表中书名为"现代网络技术基础"书的总编号,将查出的总编号作为给外层查询WHERE后的条件,外层循环完成的是在借阅表中总编号为内层查询查出来的结果的记录的借书证号。

单项选择题
单项选择题

There (1) not one type of reading but several according to your reasons for reading. To read carefully, you have to (2) your reading speed and technique (3) your aim (4) reading. Skimming is a technique necessary for quick and efficient reading.

When skimming, you (5) the reading (6) quickly in order to get the (7) of it, to know how it is organized, (8) an idea of the tone or the intention of the writer. Skimming is (9) an activity which (10) an overall view of the text and (11) a definite reading competence.

Skimming doesn’t need reading all the material, but it doesn’t mean that it is an (12) skill for the lazy, because it need a high degree of alertness and concentration.

When you read, you usually start with (13) understanding and move towards detailed understanding rather than working the other way round. But (14) is also used after you have already carefully studied and you need to (15) the major ideas and concepts.

In order to be able to skim quickly and (16) through a text, you should know where to look for what you want. In preview skimming you read the introductory information, the headings and subheadings, and the summary, if one is provided. (17) this skimming, decide whether to read the material more thoroughly, and select the appropriate speed (18) you read.

The same procedure (19) for preview skimming could also be used to get an overview. Another method would be to read only key words. This is done by omitting the unnecessary words, phrases, and sentences.

In order to skim efficiently and fulfill your purpose, (20) practice is necessary.

9().

A.however

B.nevertheless

C.therefore

D.thus