题目

China has developed rapidly since 1978.A．has a rapid developmentB．has made rapid progressC．has a great change D．has made a rapid progress 答案：B解析:略如图,点A,B的坐标分别为(2,0),(0,1),若将线段AB平移至A1B1,则a+b的值为( )A.2B.3C.4D.5