一电容器两端允许加的直流电压最大值是260 V,能否将它接在按正弦规律变化的交流

题型:问答题

问题:

一电容器两端允许加的直流电压最大值是260 V,能否将它接在按正弦规律变化的交流电压为220 V的电路中?

考点:交变电流的最大值、有效值、瞬时值和平均值
题型:问答题

As Oil Declines, So does America


More than 100 years ago, America’s first great economic (26) abroad was spearheaded by its giant oil companies, notably John D. Rockefeller’s Standard Oil Company. These companies (27) powerful beachheads in Mexico and Venezuela, and later in parts of Asia, North Africa and, of course, the Middle East. (28) they became ever more dependent on the extraction of oil in distant lands, American foreign policy began to be (29) around acquiring and protecting US oil concessions in major (30) areas.
With World War Ⅱ and the Cold War, oil and US national (31) became thoroughly intertwined. After all, the United States had prevailed over the Axis (32) in significant part because it possessed vast reserves of domestic petroleum, while Germany and Japan lacked them, depriving their forces of vital (33) supplies in the final years of the war. As it happened, though, the United States was using up its domestic (34) so rapidly that, even before World War Ⅱ was over, Washington (35) its attention to finding new overseas sources of crude oil that could be (36) under American control. As a result, Saudi Arabia, Kuwait and a host of other Middle Eastern producers would become key US oil suppliers (37) American military protection.
There can be (38) question that, for a time, American domination of world oil production would prove a potent source of economic and military power. (39) World War Ⅱ, an abundance of cheap US oil spurred the (40) of vast new industries, including civilian air travel, highway construction, a (41) of suburban housing and commerce, mechanized agriculture, and plastics.

A. DuringB. After C. Without D. Except

Abundant oil also underlay the global expansion of the country’s (42) power, as the Pentagon defended the world while becoming one of the planet’s great oil guzzlers. Its global dominion came to (43) on an ever-expanding array of oil-powered ships, planes, tanks and missiles. As long as the Middle East—and especially Saudi Arabia—served essentially as an American gas station and oil (44) a cheap commodity, all this was relatively painless. That is why the use of military force has been a (45) of American foreign policy since 1987.

题型:问答题

为有效地制约和防止会计主体通过会计方法的变更,在会计核算上弄虚作假,粉饰企业的财务状况和经营成果,企业不得任意改变会计处理方法。这体现了()原则的要求。

A.一致性

B.相关性

C.重要性

D.可比性

题型:问答题

混凝土泵是利用压力沿管道将混凝土拌合物连续输送到浇筑地点的建筑施工机械,其最大输送()。

A.水平距离可达500m,垂直距离可达50m

B.水平距离可达600m,垂直距离可达100m

C.水平距离可达700m,垂直距离可达200m

D.水平距离可达800m,垂直距离可达300m

题型:问答题

出洞和洞内的对比是nature和()的对比。

A.law

B.good

C.justice

D.ethics

题型:问答题

项目融资与公司融资的比较分析.

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