摩擦表面应比非摩擦表面的表面粗糙度数值小。
参考答案：对
He is very popular among his students as he always tries to make them_________ in his lessons. [ ]
A. interested
B.interesting
C. interest
D.to interest
“系统分析”一词最早是在20世纪30年代提出的，当时是以( )为主要应用对象。
A．问题分析B．问题诊断C．管理问题D．解决问题
