圆形截面轧材，如圆钢、圆形钢管的截面上出现两个相互垂直直径不等的现象叫（）。
A．椭圆度
B．垂直度
C．尺寸超差
D．弯曲度
参考答案：A
We went through a period ______ communications were very difficult in the rural areas. [ ]
A. which
B. whose
C. in which
D. with which
治疗帕金森常用的药物有（）
A.安坦
B.胞二磷胆碱
C.美多巴
D.金刚烷胺
E.溴隐亭
