题目

如图所示，小金同学将数枚一元硬币放在两根平行的条形磁铁上，搭成了一座漂亮的“硬币桥”，下列说法正确的是( ) A . “硬币 桥”上最外侧的硬币没有磁性 B . “硬币桥”最中间的磁性最强 C . 两枚硬币的相邻部分是同名磁极 D . “硬币桥” 的搭建利用了磁化的原理 答案：D     For Barack Obama,public service has been the cause of his life. Obama began his career by moving to the South Side of Chicago to direct the Developing Communities Project,an organisation 1.(form) to improve living conditions in poor neighborhoods. After graduating from law school,Obama passed up law firm jobs to head Project Vote,2. helped register 150,000 new African-American voters in Chicago,the 3.(high) number ever registered in a single local effort. Michelle Obama was in charge of Public Allies Chicago,a leadership development program that prepares talented young adults for careers 4.(serve) the public good. Barack Obama believes public service helps both the individuals that serve 5. the communities that benefit.     Barack Obama calls his years working as a  community organiser in Chicago,s South Side the best education he ever 6. (have) . He believes that all students should serve 7.(they) communities. Studies show that students who participate 8. service-learning programs do better in school,are more likely to graduate from high school and go to college,and are more likely to become active 9. (citizen) . Schools that require service as part of the 10. (education) experience create improved learning environments ;and serve as resources for their communities.