卡网点在办理退款后，需按收回的发票金额开具红字销售发票，并（）金额开具销售发票。 A

慢性病性贫血铁代谢的特征是（）

A.血清铁正常，铁蛋白下降，总铁结合力上升

B.血清铁正常，铁蛋白正常，总铁结合力正常

C.血清铁下降，铁蛋白升高，总铁结合力下降

D.血清铁下降，铁蛋白下降，总铁结合力下降

E.血清铁升高，铁蛋白升高，总铁结合力下降

在作BOD5和DO测定时，不需要排除（）的干扰。

A.氧化物

B.氯化物

C.硝化物

D.氰化物

女，9个月，近3个月反复呼吸道感染伴慢性中耳炎，出生时反复严重惊厥，血钙明显低下，经静脉补充钙剂、止痉剂和维生素D可暂时缓解，整个新生儿期发作21次，以后渐少见，近1个月未再发作，体检一般好，心界向两侧扩大，心前区粗糙Ⅲ～Ⅳ级收缩期杂音，白细胞1×10⁹/L，中性粒细胞0，淋巴细胞0，淋巴细胞增殖反应低下，NBT80%，最可能的诊断是：（）

A.X-连锁无丙种球蛋白血症

B.慢性肉芽肿病

C.胸腺发育不良

D.白细胞黏附分子缺陷病Ⅰ型

E.白细胞黏附分子缺陷病Ⅰ型

男性患者，32岁，头晕，乏力，心悸，查体：抬举样心尖搏动，胸骨右缘第2肋间3/6级收缩期粗糙喷射样杂音，向颈部传导，该患者的诊断是

A．主动脉瓣关闭不全

B．主动脉瓣狭窄

C．肺动脉瓣狭窄

D．二尖瓣狭窄

E．二尖瓣关闭不全

Many people are concerned about the economic condition of developing countries — countries whose average per capita GNP is a fraction of that in more industrialized countries. However, for the developing countries, there exist many obstacles to their economic development.

One major obstacle to economic development is population growth. (46) The populations of most developing countries grow at a rate much faster than those of industrialized countries, and the population of some of them is so large that there is barely enough fertile land and other resources to support it. Many less developed countries depend extensively on agriculture, adding to the problem. In these countries, an incentive to have many children exists. (47) Most farms are worked by families, and children can work in the fields at an early age because most farmers believe that more children means more workers. In addition, having many children ensures the parents that someone will look after them in their old age.

Another problem for developing countries is increasing average life expectancy—the average remaining lifetime for persons who reach a certain age. Better education, international aid, and emphasis on health-care facilities help people live longer. A high life expectancy coupled with a high crude birthrate makes it difficult to increase per capita GNP.

Another obstacle to economic growth is limited natural resources. No country can develop beyond its resource potential. Unproductive land or a harsh climate can limit economic growth. (48) Some countries may be fortunate enough to discover a valuable mineral to finance their economic development, but most focus on agriculture and, as a result, their economic growth is hindered by the shortage of natural resources or energy sources needed for industry.

Still another obstacle to economic development is a lack of appropriate education and technology. Any developing countries do not have a highly literate population or the high level of technical skills needed to build an industrial society. In addition, most do not have money to train engineers and scientists. (49) Many developing countries cannot even afford to provide free public education for school-age children, and in those that can, not every child is able to take advantage of it because most of them have to work to help feed their families. As a result, much of the population may not have the basic skills needed to continue with higher education when it is offered.

Government also can be an obstacle to economic development. A country whose government often changes will have a hard time developing economically. Such constant changes impede long-term planning. (50) Economic development is made even more difficult if the political changes occur through violent revolution where industrial facilities may be destroyed.

(46) The populations of most developing countries grow at a rate much faster than those of industrialized countries, and the population of some of them is so large that there is barely enough fertile land and other resources to support it.