Well, it really happens throughout development and it happens from the first stages.

这一过程不仅贯穿整个发育阶段,并且于胚胎发育伊始就存在

耶鲁公开课 - 生物医学工程探索课程节选

So, for example, Wellbutrin, it is very unlikely that it would have thionyl chloride in order to make it, and if thionyl chloride was used at some point in the synthesis, it was not to put that chlorine atom on, it was to put something else on.

比如，安非他酮，用亚硫酰氯来制造它,是不太可能的，而就算在合成过程中的某一阶段用到了亚硫酰氯，它也不会把氯原子加进去，而是把其它东西加进去。

麻省理工公开课 - 化学原理课程节选

During development now this blastocyst has become implanted.

现在囊胚已经到了发育过程中的着床阶段

耶鲁公开课 - 生物医学工程探索课程节选

This Cambridge History of Food talks about three separate primary phases in human food evolution: one beginning a million and a half years ago, another about 700,000 years ago, and then the 10,000 year ago one that I talked about just a moment ago.

剑桥饮食史》描述了,人类饮食结构演化过程中的三个不同阶段,其一,始于一百五十万年前,其二,距今约七十万年,其三,距今一万年,我们刚讨论过了

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选