富有“黄土风情”特色的民俗文化是（   ）

如图，在已知的△ABC中，按以下步骤作图：

①分别以B，C为圆心，以大于$\frac{1}{2}$​BC的长为半径作弧，两弧相交于两点M，N；

②作直线MN交AB于点D，连接CD．

若CD=AC，∠B=25°，则∠ACB的度数为（　　）

   About 21,000 young people in 17 American states do not attend classes in school buildings.
   Instead, they receive their elementary and high school education by working at home on computers. The center for Education Reform says the United States has 67 public “cyberschools(网络学校)” and that is about twice as many as two years ago.
   The money for students to go to a cyberschool comes from the governments of the states where they live. Some educators say cyberschools receive money that should support traditional public schools. They also say it is difficult to know if students are learning well.
Other educators praise this new form of education for letting students work at their own speed. These people say cyberschools help students who were unhappy or unsuccessful in traditional schools. They say learning at home by computer ends long bus rides for children who live far from school.
   Whatever the judgment of cyberschools, they are getting more and more popular. For example, a new cyberschools called Commonwealth Connections Academy will take in students this fall. It will serve children in the state of Pennsylvania from ages five through thirteen.
Children get free equipment for their online education. This includes a computer, a printer, books and technical services. Parents and students talk with teachers by telephone or by sending emails through their computers when necessary.
   Students at cyberschools usually do not know one another. But 56 such students finished studies at Western Pennsylvania Cyber Charter School recently met for the first time. They were guests of honor at their graduation.