题目

2001年，日本科学家发现了便于应用、可把阻抗降为零的由硼和镁两种元素组成的超导材料。这是27年来首次更新了金属超导体的记录，是目前金属化合物超导体的最高温度。该化合物也因此被美国《科学》杂志评为2001年十大科技突破之一。下图是该化合物的晶体结构单元，镁原子间形成正六棱柱，且棱柱的上下底面还各有一个镁原子，6个硼原子位于棱柱内。则该化合物的化学式可表示为( ) A.MgB                                B.MgB2C.MgAcross the world, 1.1 billion people have no access to clean drinking water. More than 2.5 billion people lack basic sanitation.(卫生设备)The combination proves deadly. Each year, diseases related to inadequate water and sanitation kill between 2 and 5 million people and cause an estimated 80 percent of all sicknesses in the developing world. Safe drinking water is a precondition for health and the fight against child death rate, inequality between men and women, and poverty.Consider these facts:●The average distance that women in Africa and Asia walk to collect water is 6 kilometers.●Only 58 percent of children in sub-Saharan Africa are drinking safe water and only 37 percent of children in South Asia have access to even a basic toilet. ●Each year in India alone, 73 million working days are lost to water-borne diseases.Here are three ways you can help:1) Write CongressCurrent U.S. foreign aid for drinking water and sanitation budgets only one dollar per year per American citizen. Few members of Congress have ever received a letter from voters about clean drinking water abroad.2) Sponsor a project with a faith-based organizationMany U.S. religious groups already sponsor water and sanitation projects, working with partner organizations abroad. Simply put a single project by a U.S. organization can make safe water a reality for thousands of people.3) Support nonprofit water organizationsNumerous U.S.-based nonprofits work skillfully abroad in community-led projects related to drinking water and sanitation. Like the sample of non-profits noted as follows, some organizations are large, other small-scale, some operate worldwide, others are devoted to certain areas in Africa, Asia, or Latin America. Support them generously.68. The three facts presented in the passage are used to illustrate that________.A. poverty can result in water-borne diseasesB. people have no access to clean drinking waterC. women’s rights are denied in some developing countriesD. safe drinking water should be a primary concern69. The main purpose of the passage is to call on people to _________.A. get rid of water-related diseases in developing countriesB. donate money to people short of water through religious groupsC. fight against the worldwide water shortage and sanitation problemD. take joint action in support of some nonprofit water organizations70. What information will probably be provided following the last paragraph?A. A variety of companies and their worldwide operation.B. A list of nonprofit water organizations to make contact with.C. Some ways to get financial aids from U.S. Congress.D. A few water resources exploited by some world-famous organizations.