在15世纪,印刷术得到发展,纸张成为欧洲书籍的主要材料,在此之前的主要材料是羊皮纸。
During the 1400s, when printing was being developed, paper became the predominant material for books in Europe, but prior to that, it was parchment.
在此之前的时期是最危险的。
在此之前的那天晚上,弗农和安。乔丹夫妇也邀请了一些人与我们一起进餐。
The previous night, Vernon and Ann Jordan had also invited some people to have dinner with us.
But before I tell you about lab experiments let me tell you about the most famous field experiment on this idea.
但是,在此之前,让我告诉你们关于这个观点最著名的现场试验。
Before that, diabetics had been treated with insulin that came from a different source, usually from pigs, so by harvesting and purifying insulin from pig pancreas.
在此之前 糖尿病患者,所用的胰岛素来自于不同的来源,通常是从猪身上提取的,是从猪的胰腺中提取并纯化而成的
I should have also mentioned another really important information technology that developed in the nineteenth century was the Postal Service, although we had mail before then.
我应该也提到过,另一个产生于19世纪的,非常重要的信息技术,就是邮政服务,虽然我们在此之前就有信件往来。
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