题目

 Papermaking began in China and from here it _______ to North Africa and Europe. A. spread    B. grew   C. carried   D. developed 答案：A在平行四边形ABCD中，AC与BD交于点O，E是线段OD的中点，AE的延长线与CD交于点F。若=a，=b，则= [     ]A、B、C、D、