TJWX-2000监测系统中车站系统由信息采集隔离模块、下位集中式信息采集机、CAN卡和上位机等部分组成。
参考答案：错
I often wrote to him in the past, but he never _____ to any of my letters. [ ]
A. reached
B. realized
C. replied
D. refused
X线照片上相邻两点之间的密度差是（）
A.密度
B.对比度
C.清晰度
D.锐利度
E.失真度
