车辆识别信息编码由（）位组成.

阅读理解。

     All big cities are quite similar (相似的). Living in a modern Asian city is not very different from living in

an American city.But it is different from living on farms, however.

     In many parts of the world, farmers and their families live in villages or towns. In the United States,

however, each family lives on its own fields, and often can't see any neighbor. Instead of traveling from a

village to the fields every morning. American farmers stay on their land all the week. They travel to the nearest

town on Saturdays for shopping or on Sundays for church. The children ride on horses to large schools which

serve all of the farm families living in the area. In some areas, there are some small schools serving a few

families, and the children walk to school. 

     Of course, life keeps changing for everyone, including farmers. Today, there are cars, good roads, radios

and television sets. And of course there are modern machines for faming. All of this have changed farm life. 

     For many years, however, farming in America was often a lonely way of living.Farmers had to deal with

their own problems,instead of getting help from others. They learned to try new ways and to believe their

ideas instead of following old ways.

1.Living in the big cities ______ living on the farm. [ ]

A. the same as

B. different from

C. similar

D. just like

2. American farmers have their own ______.[ ]

A. villages

B. towns

C. fields

D. church

3. Farmers stay on their farm ______ in America instead of traveling from a village to the fields every

    morning. [ ]

A. all the week

B. every day

C. from Monday to Friday

D. on Saturday and Sunday

4.The life on the farm changes ______ now. [ ]

A. good

B. better

C. bad

D. worse

5. Why does the writer say "farming in America was often a lonely way of living"? [ ]

A. Because they learned to try new ways.

B. Because they had to deal with their own problems.

C. Because farm life changed a lot.

D. Because the children had to ride on horses to large schools.

在串联电路中，若R₁∶R₂=5∶2，则通过这两个电阻的电流之比为        ，R₁ 与R₂两端的电压之比              。

在进行全站停电操作时，应先将电容器组的开关断开，然后再停各分路的（）。

变频器的输出频率可以分段运行，分段运行又分为“程序运行”和“外端子控制运行”，解释这两种段速运行的主要区别。

苗木