There are two upright struts of the ladder, one shown in blue here, the other shown black.

两条上下的主链作为支柱,一条以蓝色表示,一条以黑色表示

耶鲁公开课 - 生物医学工程探索课程节选

Here is the lady's scarf, very hot, black.

这儿有一条女士围巾，很流行，黑色的。

麻省理工公开课 - 固态化学导论课程节选

And you get that reinforced on the very next page if you just skip over about a page from there: "A black pickup truck turned off a side road in front of him.

当你看到下一页时,这种感觉会加强,直接往后跳过一页：,“一辆小型黑色货车,在他面前拐进一条小路。

耶鲁公开课 - 1945年后的美国小说课程节选

The corresponding half of the ladder that corresponds to any given ladder, let's say the black DNA molecule that corresponds to the blue one is not just a mirror image.

与任何单链配对的,另一条单链,比方说与蓝色DNA分子,配对的黑色DNA分子,并不是蓝色DNA分子的镜像

耶鲁公开课 - 生物医学工程探索课程节选