集合A={1，2}的子集有几个（） A．2 B．4 C．3 D．1_爱下问搜题

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问题选择题

集合A={1，2}的子集有几个（　　）

A．2

B．4

C．3

D．1

答案

集合A={1，2}的子集有：?，{2}，{1}，{2，1}共4个．

故选B．

问答题简答题

802.11协议簇定义了多种WLAN接入标准，目前采用最为广泛的标准是什么？

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．vehicles

B．buses

C．transport

D．films