用常系数微分方程描述的系统称为（）系统。
A.相似
B.物理
C.力学
D.线形
参考答案：D
We don’t care about how Obama won the Nobel Peace Prize but _______matters for us is ______he will make his effort to bring a peaceful world to us. （原创）
A．that; how
B．which; whether
C．it; that
D．what ; whether
下面不属于Windows98的通信组件的是______。
A．拨号网络
B．虚拟专用网络
C．Netshow
D．Outlook
