f（x）=（1+2x）m+（1+3x）n（m，n∈N*）的展开式中x的系数为13

透明网桥可以决定网络中的路由，而网络中的各个站点均不负责路由选择。网桥具有帧过滤功能，网桥从其某一端口收到正确的数据帧后，在其地址转发表中查找该帧要到达的目的站，若查找不到，则会 (243) ；若要到达的目的站仍然在该端口上，则会 (244) 。图3.1为两个局域网 LAN1和LAN2通过网桥1和网桥2互连后形成的网络结构。设站A发送一个帧，但其目的地址均不在这两个网桥的地址转发表中，这样结果会是该帧 (245) 。为了有效地解决该类问题，可以在每个网桥中引入生成树算法，这样一来 (246) 。

图3.2为一10Mbps数据传输率下的以太网，其上连接有10个站，在理想状态下每个站的平均数据传输率为1Mbps。若通过网桥连接后成为图三所示的结构时，每个站的实际有效数据传输率为 (247) Mbps。

（247）处填（）

A.1～2

B.1

C.2

D.0～1

Do you suppose Darwin, one of the greatest scientists of all time, really did foolish experiments? Or did he do experiments that were so simple and basic that other people just thought they were foolish?

Sometimes, people think they already know the answer to a question or the solution to a problem. Sometimes, they really do know an answer or a solution, but without thinking they are important.

Charles Darwin didn’t settle for(满足于)just thinking he knew something. And, he believed all things could be important however simple they seemed to be.

Suppose you drop sheets of paper that are of exactly the same size and shape. If you drop them at the same time in the same place, they will fall in the same way. Now make one of the sheets of paper into a tight little ball and let it drop along with the other sheets. What happens? You have done an experiment that is so simple that you might think it couldn’t be worth anything.

But this simple experiment is important. It explains part of our present-day understandings of physics, ideas that were worked out long ago by Galileo and Newton. And these understandings set aside some of ancient Greek physics.

Scientists sometimes stop to look at very simple things and to think very hard about them. Even the simplest idea, which we might think is foolish, can shake the foundations of science.

小题1: The passage tells us that Charles Darwin　　　　.

A．was a great English scientist

B．always liked doing the experiments that others thought difficult

C．thought even the simplest thing was important

D．didn’t get well with others小题2: The underlined phrase “set aside” most probably means　　　　.

A．throw away

B．store up

C．put to use

D．realize小题3: The author of the passage tries to　　　　.

A．convince us that Charles Darwin, Galileo and Newton are the greatest scientists in the world

B．draw the conclusion that basic sciences are simple things

C．prove that two sheets of paper, with the same size and shape, will fall at the same speed

D．draw our attention to everyday happenings around us小题4:Which of the following is TRUE?

A．Darwin really did foolish experiments.

B．According to some people Darwin did foolish experiments.

C．It is believed by all the people that things could be important though they seemed to be simple.

D．Galileo and Newton worked out ancient Greek physics.

下列选项中有权决定乡、民族乡、镇的建置和区域划分的是( )。

A．国务院

B．省、直辖市的人民政府

C．自治州、设立的市的人民政府

D．县级人民政府

对现金流不能够全覆盖贷款，项目能够吸引社会资金投资的政府融资平台，要（）。

A.收回再贷

B.引资还贷

C.据实定贷

D.只收不贷