题目

By the end of last month, we ______________ all the new lessons. A . have learned B . learned C . had learned D . would learn 答案：C如图，Rt△ABC中，∠C=90°，∠A=30°，AB=2．（1）用尺规作图，作出△ABC绕点A逆时针旋转60°后得到的△AB1C1（不写画法，保留画图痕迹）；结论：______为所求．（2）在（1）的条件下，连接B1C，求B1C的长．