选矿厂的圆锥选矿机采用将分选锥垂直多层配置。其中能实现连续的（）选作业。
参考答案：粗、精、扫
Distinguished guests and friends, welcome to our school. __________ the ceremony of the 130th
Anniversary are our schoolmates from home and abroad. [ ]
A. Having attended
B. Attending
C. To attend
D. Attend
为了提高测试的效率，应该______。
A．随机地选取测试数据
B．取一切可能的输入数据作为测试数据
C．在完成编码以后制定软件的测试计划
D．选择发现错误可能性大的数据作为测试数据
