单项选择题网络攻击的发展趋势是( ) A. 黑客技术与网络病毒日益融合 B. 攻击工具日益先进 C. 病毒攻击 D. 黑客攻击
单项选择题A higher order system is implemented by the cascading or paralleling of several sub-systems. If we want the poles of the original system is same as those of the sub-systems, then we can adopt the( )