First let me back up a bit and talk about vision correction before the printing press.
让我先回顾下在印刷术之前的视力矫正是什么样的。
2
Once the printing of unbacked money slows down or stops altogether, this stops the flow of real savings to various activities that emerged on the back of unbacked money.
一旦减缓或者停止印刷没有支撑的纸币，这将停止真实的储蓄流向由没有支撑的纸币引发的各种活动。
3
Most processes can trace their roots back to the earliest form of 3-d printing: stereolithography.