应用AutoCAD软件进行打印，既可以用系统打印机，也可以定义非系统打印机。
参考答案：对
比较大小：3+7+2○15-3+1。
They are so close friends and their friendship _____ college days.[ ]
A. dates back to
B. dates back
C. dates to
D. dates back from
