Realizing that he would be late for school, little Tom had ___of the bread prepared by Mum and hurried out.

A．nothing

B．all

C．neither

D．none

开放系统参考模型(OSI/RM)的结构分为七层，由下往上依次为物理层、数据链路层、网络层、传输层、会话层、 【10】 和应用层。