单项选择题
A.2000×(1-10-5) B.2000×10-5 C.1-(1-10-5)2000 D.(1-10-5)2000
A.255.255.255.192 B.255.255.255.224 C.255.255.255.240 D.255.255.255.248
A.7 B.9 C.5 D.13