In politics,a dark-horse candidate is someone who is not well known to the public.

VOA: special.2009.07.12

Well, the ones in director light must not be so reflective but be kind of of dark surface.

然而，直接处于光线之下的瓷片不会如此反光,它们的表面较暗。

斯坦福公开课 - 7个颠覆你思想的演讲课程节选

It's just not the color for you. It's too dark.

这个颜色不怎么适合你。看起来太深了。

I hate 实战 - SpeakingMax英语口语达人

The key line in the society of the Dark Ages appears to be certainly not between monarchy and everybody else, but between nobility and commoners.

黑暗时代的社会中,最重要的主线,显然不是君主阶级和平民们之间,而是贵族和平民之间

耶鲁公开课 - 古希腊历史简介课程节选

It's dark. The other, dark, in the sense of gloomy, not good, bad; this is a hard time, a poor time, a wretched time, a miserable time.

因此称之为黑暗,另一个理由是,黑暗从悲观的角度来说就是不好的,坏的,这是一个艰难的时代,一个穷苦的时代,一个不幸的时代,一个悲惨的时代

耶鲁公开课 - 古希腊历史简介课程节选

Now, I've been saying kind things about Western civilization, but I would not want to deny that there is a dark side to the western experience and its way of life.

我刚刚一直说的都是西方文明光辉的一面,但我是不得不承认,西方文明,也有它黑暗的一面

耶鲁公开课 - 古希腊历史简介课程节选