下列图形中，既是中心对称图形又是轴对称图形的是（ ） A．正六边形 B．平行四边

电流互感器长时间过负荷运行会（）。

A、误差增大

B、表计指示不正确

C、磁通密度增大

D、绝缘老化加快

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.

小题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小题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.小题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小题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.

孙某在甲企业申请注册为注册安全工程师。当地另有一家从事安全生产中介服务的乙公司，欲聘请孙某在乙公司兼职从事安全技术服务工作。依据《注册安全工程师管理规定》，下列关于孙某受聘的说法中，正确的是（）。

A．孙某受聘于甲企业，不能从事任何兼职活动 

B．孙某可以接受聘请，但不能以乙公司注册安全工程师名义执业 

C．孙某在乙公司申请注册后，可以以乙公司注册安全工程师名义兼职执业 

D．孙某在征得甲企业同意之后，可以以乙公司注册安全工程师名义兼职执业

下面选项中，不正确的是（）。

A．行政经费属于社会消费性支出

B．国防支出属于非生产性支出

C．司法机关的经费不属于行政管理经费

D．国防支出对于国家的存在是十分重要的

数字化通用式机车信号主机电源块输入为50V，输出为（）V。

A.24土0.5

B.24土1

C.12

D.5