问题 单项选择题

在OSI参考模型中,物理层通过物理连接在 (1) 之间提供比特流的传输;数据链路层通过数据链路在 (2) 之间提供数据链路进行服务单元透明传输;网络层通过网络连接在 (3) 之间交换网络服务数据单元;传输实体向 (4) 提供面向连接的传输服务。在应用层提供的公共应用服务元素CASE、特定应用服务元素SASE和用户元素UE中,作为系统与用户进程交互手段的是 (5)

A.物理层实体

B.数据链路层实体

C.网络层实体

D.传输层实体

答案

参考答案:C

阅读理解

阅读理解

       Can animals be made to work for us? Some scientists think that one day animals may be taught to

do a number of simple jobs. They say that in a film or on TV we may see elephants, monkeys, dogs,

bears, or other animals doing a lot of things. If you watch carefully, you may find that those animals are

always given something to eat in return for doing them. The scientists say that many different animals may

be taught to do a number of simple jobs if they will get something in return.

       Of course, as we know, dogs can be used to guard a house, and elephants can be used to do some

heavy jobs. And we can also teach animals to work in factories. Apes, for example, have been used in

America to help make cars and scientists believe that these large monkeys may one day get in crops and

even drive trains.

1. Elephants can be used to do some heavy jobs because____________.

A. they can eat a lot

B. they are very heavy, too

C. they are very strong

2. Dogs van be used to guard a house for his host because____________.

A. they are good at running

B. they are very kind and friendly to people

C. they are brave enough to get the stranger and thieves away from house

3. Many different animals may be taught to do some simple jobs if __________.

A. they have enough food to eat

B. they learn they will get something to eat in return after doing them

C. they are sent to school

4. ______________ can be trained for us.

A. Only a few animals

B. Quite a few animals

C. Few animals

5. Many scientists are working hard to _____.

A. make monkeys get in crops and drive trains

B. make monkeys guard a house like dogs

C.make bears get in crops

单项选择题 A1/A2型题