Gutenberg invented printing, the most consequential invention of the Middle Ages. The technical adventure of Gutenberg is very impressive. The printing press, the paper, the ink... . He manages to assemble all of these items, and to actually print books. Gutenberg tries a new form of layout and introduces a number of other innovations. The visual quality of his printing yields ..苍蝇没事的时候为什么要搓搓手,搓搓脚?开饭之前先洗手…