— Will you stay for lunch? 

— Sorry, ______. My brother is coming to see me. [ ]

A. I mustn't

B. I can't

C. I needn't

D. I won't

某校园网的地址块是138.138.192.0/20，该校园网被划分为（48） 个 C 类子网，不属于该校园网的子网地址是（49） 。

A．138.138.203. 0

B．138.138.205.0

C．138.138.207. 0

D．138.138.213.0