问题 问答题

为以上建立的联系设置参照完整性约束:更新规则为“限制”;删除规则为“级联”;插入规则为“限制”。

答案

参考答案:STEP 01 从“数据库”菜单中选择“清理数据库”命令。
STEP 02 右键单击表“dept”和表“salary”之间的连线,选择“编辑参照完整性”命令。
STEP 03 在“参照完整性生成器”对话框的“更新规则”属性页中选择“限制”项,在“删除规则”属性页中选择“级联”项,在“插入规则”属性页中选择“限制”项,单击“确定”按钮。

阅读理解

阅读理解。

     In the computer age, most of us take a broadband Internet connection for granted. Whether cable or mobile

broadband, today's connections are many times faster than those in the early days. Videos play smoothly,

complex websites load quickly, and files download much faster than ten years ago. And the files are much

bigger too.

     There's a catch, of course. You have to live near enough to a major city to get broadband Internet. If you

don't, it's slow dial-up access for you. And for those living really far out, there may be no Internet access at all.

     Technology experts often talk about the "last mile" problem, which refers to the difficulty of bringing

Internet access to remote locations. In cities and suburbs, it's relatively easy to provide access for everyone.

It is much more difficult to deliver access to those living far from cities, especially in developing countries.

Internet service providers, for their part, have been reluctant to provide access to sparsely (稀疏地) populated

areas. The handful of Internet users they would reach wouldn't cover the expense.

     But every year, technological advancements allow of more and more Internet users. Most broadband

connections today run over existing cable TV and telephone lines although these technologies aren't available

everywhere. Some companies have delivered the Internet over standard power lines. Advancements in cheaper, more efficient fiber optics cables (光纤电缆) promise to bring extremely fast Internet connections to more

users.

     Still, the "last mile" problem remains hard to deal with. There will always be somewhere that doesn't have

an affordable broadband connection. But someday that might not matter. If the rapid progress in cell phone

technology is any indication (迹象), it may not be too long before an Internet connection simply follows you

wherever you go.

1. The underlined part " a catch" (in Paragraph 2) probably means "_____".

A. a rare challenge

B. a desirable plan

C. an efficient device

D. a hidden problem

2. What can we know from the third paragraph?

A. Internet connection has not been popular in most cities.

B. Internet service providers care about rural customers.

C. Computer is popular in developing countries.

D. It is hard to bring Internet access to users in remote areas.

3. Paragraph 4 mainly tells us that technological advancements ______.

A. make TV and telephone available everywhere

B. bring great change to people's everyday life

C. make it possible for more people to use the Internet

D. bring faster Internet connections to users

4. What may eventually settle the "last mile" problem?

A. The broadband connection's getting faster.

B. More and more Internet users.

C. More and more Internet connections.

D. The rapid progress in cell phone technology.

单项选择题