题目

_____Macao has achieved shows _____one country, two systems principle is the best solution to the Macao and Hongkong question, left by history. A . That; what B . What; that C . What; what D . That; that 答案：B把一张矩形纸片ABCD按如图方式折叠，使顶点B和顶点D重合，折痕为EF，若BF=4，FC=2，则∠DEF的度数是（    ）。