轴线垂直于正投影面的正圆锥体，其上的投影图为______。
A．正方形
B．圆
C．三角形
D．扇形
参考答案：B
He came to my class every week, but his look that he was not really interested．
A．expresses
B．described
C．explained
D．suggested
该单位的公网IP地址范围是 (1) 到 (2) ；其中该单位能够使用的有效公网地址有 (3) 个。
