题目

All those second­hand computers are sold in this shop at ________ before. A. 50% as lower price as     B. as 50% low price as    C. 50% lower price than      D. 50% as low a price as   答案：D   写出下列多项式的项、项数和次数 (1)x2－y3 (2)－mn＋m－n＋1