题目

The discussion has been based on ______ consideration of the performance of the group of learners as ______ whole. A．the; a           B．a; a           C．a; the          D．the; the 答案：A画一个菱形ABCD，使对角线长AC=a，BD=b（要求：用尺规作图，保留作图痕迹，不写出已知、求作、作法和证明）．