There ____________ no milk in the fridge a moment ago.[ ]
A. are
B. was
C. were
答案:B
有4个B类网络地址:130.57.16.254、130.57.17.01、130.57.32.254和130.57.33.01。如果子网掩码为255.255.240.0,则下列说法中正确的是()。
A.130.57.16.254和130.57.32.254属于同一子网
B.130.57.16.254和130.57.17.01属于同一子网
C.130.57.16.254和130.57.33.01属于同一子网
D.130.57.17.254和130.57.32.254属于同一子网
简述烟气中有害物质的类别。