桥吊起升及小车运行机构使用()控制。A、V/F控制B、速度闭环矢量控制C、电压矢量控

题型:单项选择题

问题:

桥吊起升及小车运行机构使用()控制。

A、V/F控制

B、速度闭环矢量控制

C、电压矢量控制

D、直接转矩控制

考点:安全科学技术安全人机学安全人机学题库
题型:单项选择题

下图为反映某国经济的一般均衡模型。该国生产食品(纵轴)和衣着(横轴)两种商品,假定食品生产为资本密集型,衣着生产为劳动密集型。图中曲线PP为该国的生产可能性曲线,U1和U2 为两条不同水平的效用曲线,直线R的斜率反映国际市场上两种商品的交换比价。根据该图回答下列问题:

开放贸易后该国两种产品的产出组合为( )点,消费组合为( )点,实现的效用水平为( ),出口的商品为( ),进口的商品为( )。

题型:单项选择题

“海洋科学技术的一场革命”指的是什么?

题型:单项选择题

下列不属于罗马法的物法的范围的是:

A.物权

B.亲属

C.继承

D.债

题型:单项选择题

集装箱运输中,FCL—FCL的交接方式是()。

A.CY/CY

B.CY/DOOR

C.CFS/CY

D.CY/CFS

题型:单项选择题

Exactly where we will stand in the long war against disease by the year 2050 is impossible to say. (46) But if developments in research maintain their current pace, it seems likely that a combination of improved attention to dietary and environmental factors, along with advances in gene therapy and protein targeted drugs, will have virtually eliminated most major classes of disease.

From an economic standpoint, the best news may be that these accomplishments .could be accompanied by a drop in health-care costs. (47) Costs may even fall as diseases ’are brought under control using pinpointed, short-term therapies now being developed. By 2050 there will be fewer hospitals, and surgical procedures will be largely restricted to the treatment of accidents and other forms of trauma. Spending on nonacute care, both in nursing facilities and in homes, will also fall sharply as more elderly people lead healthy lives until close to death.

One result of medicine’s success in controlling disease will be a dramatic increase in life expectancy. (48) The extent of that increase is a highly speculative matter, but it is worth noting that medical science has already helped to make the very old (currently defined as those over 85 years of age) the fastest growing segment of the population. Between 1960 and 1995, the U.S. population as a whole increased by about 45%, while the segment over 85 years of age grew by almost 300%. (49) There has been a similar explosion in the population of centenarians, with the result that survival to the age of 100 is no longer the newsworthy feat that it was only a few decades ago. U.S. Census Bureau projections already forecast dramatic increase in the number of centenarians in the next 50 years: 4 million in 2050, compared with 37, 000 in 1990.

(50) Although Census Bureau calculations project an increase in average life span of only eight years by the year 2050, some experts believe that the human life span should not begin to encounter any theoretical natural limits before 120. years. With continuing

(50) Although Census Bureau calculations project an increase in average life span of only eight years by the year 2050, some experts believe that the human life span should not begin to encounter any theoretical natural limits before 120. years.

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