题目

下列各组元素性质的递变错误的是（    ）A.Li、Be、B原子最外层电子数依次增多B.P、S、Cl元素的最高正化合价依次升高C.B、C、N、O、F原子半径依次增大D.Be、Mg、Ca、Sr、Ba的失电子能力依次增强 答案：解析：本题考查的知识点是同周期同主族的递变规律。对于同周期元素，自左向右，最外层电子数依次增多；最高正价依次增大；原子半径依次减小。对于同主族元素，自上到下，失电子能力逐渐增强，得电子能力逐渐减弱。Li、Be、B都是第2周期元素，自左向右依次排列，根据元素周期律，其最外层电A new report says African governments are ill prepared to handle the growing number of people over age 65. The population in Africa  as in other parts of the world, is getting older. Currently, there are 36 million people on the continent 65 years and above. which is 3.6 percent of the population. up from 3.3 percent 10 years ago. That could rise to 4.5 percent by 2030 and 10 percent by 2050. The African development Bank is raising concerns over the shortage of health insurance and pensions (养老金).      The African Development Bank says. "Aging is highly linked with long-term physical and mental  disability and a number of long-term chronic (慢性的) conditions."      "Africa is not well prepared to care for its aging population right now. And it needs to prepare for this fact." said Professor Mthuli Ncube. the African Development Bank's chief economist. African nations spend far less on healthcare than developed nations do___ about $26per person per year. Not so many countries have well developed medical aid plans for the elderly, whether they are privately provided plans or indeed government plans. If you look at the pension plans, you will find the pension industries are not well developed in some of the countries.      Professor Mthuli Ncube said African governments failed to take action on health insurance and pensions because they were busy with economic reforms.     Another challenge for Africa is the worsening of informal systems of social protection. That is cash and support from both the extended family and community sources.    . The African Development Bank recommends governments help carry out health insurance and pension plans. Ncube said African governments didn't have to handle the health insurance burden alone. "It is not only a must but also an opportunity for private companies to add their bit in this regard", he said. The report also recommends that African governments consider providing ways of free health services. medications and long-term health care facilities for the elderly. 1. From the first paragraph we know the facts except that ____ A. the speed of people aging is becoming quicker B . Africa has the largest aging population C. African governments are not well prepared to deal with the aging population D. the shortage of health insurance and pensions adds to African governments' difficulty in dealing With the aging population 2.Which is not highly linked with the aging according to the passage? A. Long-term physical disability.             B. Long-term mental disability. C. Long-term chronic illnesses.              D. Long-term shortage of care and love. 3. What got in the way of developing health insurance and pensions in Africa? A. The economic reforms.                  B. Too many old people. C. The shortage of land.                    D. The development of the economy. 4.How can the aging problem be solved in Africa according to Ncube? A. African governments should spend as much money on healthcare as developed countries B. African people should save enough money to insure their health. C. African governments should combine with private companies to finish health insurance and pension pains. D. Private sources should take the main responsibility to help the elderly. 5.The article is most likely to be seen____ A. in a story book      B. in a newspaper   C. on a TV program     D. in a textbook