请将下面这段话翻译成英文：
印刷术发明之前，想出版新书的学者必须一字一字地抄写。北宋时期，经过多年的实验，毕昇发明了活字印刷术(movable-type printing)。他把汉字刻在一小块泥胚(pieces of clay)上，加热汉字直到其变成硬的活字。印书时,人们按顺序将活字摆在一起，印出印迹。印刷完后，他们把字分开，以后重复使用。这种方法既经济又省时。中国的活字印刷术首先向东传至朝鲜和日本，之后向西传至波斯(Persia)和埃及，最后传遍全球。活字印刷术的发明大大促进了世界各国的文化交流。
参考翻译
Before printing was invented，a scholar had to copy characters one by one if he wanted to publish a new book.During the Northern Song Dynasty, Bi Sheng invented the movable-type printing after many years of experimentation.He engraved the characters on small pieces of clay,and heated them until they became hard movable characters.When printing a book，people placed the moveable characters in order into a whole block and then ran off a print.After printing, they took the block apart and reused the characters later.This method was both economical and time-saving.China's movable-type printing first spread eastward into Korea and Japan,then westward into Persia and Egypt,and at last,around the world.The invention of movable-type printing greatly promoted the cultural exchanges among countries all over the world.
附：大学英语六级翻译技巧之句式多样
可以有选择性地运用倒装结构、被动语态、否定句、虚拟语气、比较结构、从句、非谓语动词等句型，让句式结构更加丰富多彩。
例：正是通过丝绸之路，中国的'造纸、火药、指南针、印刷术等四大发明才被引介到世界各地。
一般译文：The Silk Road introduced four Chinese inventions to the world. They were papermaking, gunpowder, compass and printing.
高分译文：It was through the Silk Road that the four great inventions of ancient China, namely papermaking, gunpowder, compass and printing, were introduced to the world.
点评：“一般译文”为两个主动语态的简单句，“高分译文”将其整合成了一个被动句。把“正是……才……”处理成了“It was… that…”的强调句型，并将“造纸、火药、指南针、印刷术”处理成了插入语“namely papermaking, gunpowder, compass and printing”。