搜题请搜索小程序“爱下问搜题”
问题 单项选择题

下列要素中，不属于DFD的是 (17) 。当使用DFD对一个工资系统进行建模时， (18) 可以被认定为外部实体。

A．加工

B．数据流

C．数据存储

D．联系

答案

参考答案：D

选择题

木块沿斜面上滑，后又返回到出发点．下列各图象中能够比较正确反映该木块运动过程的是（　　）

A．

B．

C．

D．
查看答案
填空题

Part 4


Questions 26-45


·Read the following passage and decide which answer bestfits each space.
·For questions 26-45, mark one letter A, B, C or D on the Answer Sheet.
The "standard of living" of any country means the (26) person’s share of the goods and services which the country produces. A country’s standard of living, therefore depends (27) and foremost on its capacity to produce wealth. "Wealth" in this (28) is not money, for we do not live on money (29) on things that money can buy: "goods" such as food and clothing, and "services" such as (30) and "entertainment".
A country’s capacity to produce wealth depends upon many factors, most of which have an effect (31) one another. Wealth depends (32) a great extent upon a country’s natural resources. Some regions of the world are well supplied with coal and minerals, and have a (33) soil and a favorable climate; other regions (34) none of them.
Next to natural resources (35) the ability to turn them to use. China is perhaps as well off as the USA in natural resources, but suffered for many years from (36) and external wars, and for this and other reasons was incapable (37) her resources. Sound and (38) political conditions, and freedom from foreign invasion, enable a country to develop its natural resources peacefully and steadily, and to produce more wealth than another country (39) well served by nature but less well ordered.
A country’s standard of living does not only depend upon the wealth that is produced and (40) within its own borders, but also upon what is indirectly produced through international trade. For example, Britain’s wealth in foodstuffs and other agricultural products would be much (41) if she had to depend only on those grown at home. Trade makes it possible for her surplus manufactured goods to be traded abroad for the agricultural products that would (42) be lacking. A country’s wealth is, therefore, much (43) by its manufacturing capacity, (44) that other countries can be found ready to (45) its manufactures.

A．common

B．average

C．usual

D．normal
查看答案