It's here that Milton for no explicit, or no apparent, reason at all - it's here that he provides a little theoretical digression on the stunning flexibility of angelic bodies.

但在这他无缘无故的，没有任何明显原因的,-在这儿他脱离了诗歌主线,转而去描写天使身体惊人的灵活性。

耶鲁公开课 - 弥尔顿课程节选

I think the main reason is that there are no equations that involve the third derivative explicitly.

我想主要原因是因为还没有等式,明显涉及三阶导数

耶鲁公开课 - 基础物理课程节选

Another characteristic of these years, which scholars refer to as the Dark Ages, just as they do the years after the fall of the Roman Empire-- dark for two reasons. Dark, in the most obvious way, because we don't have any writing, no record of them.

这也是这段时期的另一个特征,学者们称之为,黑暗时代,他们也是这么称呼,罗马帝国陷落后的那段时期的,称黑暗主要有两个原因,黑暗,最明显的理由,是因为我们没有任何关于他们的史料和记录

耶鲁公开课 - 古希腊历史简介课程节选