问题 不定项选择题

下列有关能量转换的说法正确的是 [ ]

A.煤燃烧是化学能转化为热能的过程

B.化石燃料和植物燃料燃烧时放出的能量均来源于太阳能

C.动物体内葡萄糖氧化成CO2是热能转变成化学能的过程

D.植物通过光合作用将CO2转化为葡萄糖是太阳能转变成热能的过程

答案

AB

单项选择题

阅读下面一段资料,判断在给出的几种说法中不正确的是()。

资料:IP电话与传统电话

IP电话是按国际互联网协议规定的网络技术内容开通的电话业务,中文翻译为网络电话或互联网电话,它是利用国际互联网Inetrnet为语音传输的媒介,从而实现语音通信的一种全新的通信技术。最初的IP电话是个人计算机与个人计算机之间的通话。

IP电话与传统电话相比较,有许多不相同的地方。IP电话的传输采用Inetrnet网络,而传统电话为公众电话交换网;IP电话运用的是分组交换技术,完整的信息根据IP协议被分成一个一个分组进行传输,每个分组上都有目的地址与分组序号,到目的地后再还原成原来的信号,而且分组可以沿不同的途径到达目的地,多个分组也可以在一条线路上传输,线路不是专用的;传统电话采用的是电路交换,是通过公众电话交换网的结点在两个电话之间建立一个实际的物理连接,即形成一条专用的通信线路来完成数据传送,在通话过程中,对方会一直占用这条专用的通信线路,直到通话结束;从占用信道或带宽上讲,IP电话有信息才传送,反之不传送,这样,其语音信息不占用固定信道,使用压缩技术后,其话音信息可以压缩到8Kbit/s而传统电话一般要占用64Kbit/s的固定信道,而且只要不挂机,传统电话始终占用这一信道,所以IP电话的带宽远远低于传统电话,IP电话的资源占用更合理。IP电话的费用组成是:Inetrnet通信资费+市内电话通话资费+IP电话相关设备费用;由于现在的Inetrnet带宽、延迟、网络拥塞等因素,IP电话的语音质量还难以保证。

A、IP电话是分组交换,传统电话是电路交换。

B、IP电话是共享线路而传统电话是独占线路。

C、IP电话通话时不受带宽、延迟、网络拥堵的影响,通话质量很高。

D、通信的费用差别很大,IP电话比较便宜,尤其是在打国际长途时更能体现出来。

阅读理解

Bicycles are a great way to get around. They’re fun to ride, especially down hills. And, as you speed along the road, you might also think of ways in which you could improve your bike— make it safer, more efficient, or more comfortable. In fact, the two-wheeled machines make for some cool science projects.

This year's Intel International Science and Engineering Fair (ISEF), held last May in Cleveland, featured(had)three bicycle projects from three countries. Like many of the other experiments presented at ISEF, the bike projects showed that some of the most interesting scientific research often begins by taking a closer look at things you care about.

Renato Angulo Chu had even grander ambitions. The 12th-grader from Lima, Peru, wanted to address some of his country's economic troubles.

"I see a problem in my country," Renato said. "If you go to the forests in Peru, in some places you cannot find electricity. If you go with my bicycle, you can turn on the lights."

Renato, 16, spent 3 years designing his special Multibike. The device looks like a fixed exercise bike. It has wires fixed along the frame and a blender strapped(fastened) to the back. Turning the pedals operates the blender. The same principle can be used to sharpen knives or sweep city streets.

The Multibike can work either as a fixed bike or as a bicycle able to travel city streets and country roads. It's made from inexpensive materials, and the user gets exercise while pedaling to operate a machine.

"You pedal the bike, and you can mix any drink you want," Renato said. More importantly, he added, the same concept could be used to bring light to houses in remote regions of the rainforest.

19. What can we learn from the first paragraph?

A. Bicycles are the best way to go about

B. Bikes should be made more comfortable to ride.

C. You can improve your bicycle for science research.

D. Many inventions are connected with the bicycle.

20. Which of the following is true according to the passage?

A. ISEF is an exhibiton displaying bicycle experiments designed by students.

B. Looking closely at things you are concerned about can lead to scientific research.

C. Renato’s improvement of the bicycle has solved the country’s great problem.

D. Renato’s special bicycle will soon be put into use in remote areas.’

21. The underlined word “address” in the third paragraph probably has the same meaning as _______.

A. make address written        B. give up             C. work at             D. speak at

22. Renato’s special Multibike has all the following EXCEPT  ________.

A. making knives sharp                                     B. mixing any kind of drinks

C. producing electricity                                     D. operating a machine with its own electricity

23. It can be inferred that Renato’s special bicycle is mainly designed for ________.

A. distant areas in the rainforest without electricity.

B. the use of his own family to make life easier.

C. the competition of ISEF to win money to support remote rainforests

D. enough exercise by pedaling it