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

And here in the middle of the page a little ways down: My love's striped black-and-white cotton frock, jaunty blue cap, white socks and brown moccasins were not quite in keeping with the large, beautifully cut aquamarine on a silver chainlet which gemmed her throat, a spring rain gift from me.

在这一页中间偏下的地方：,我的小情人穿着黑白条子的棉布裙，带着鲜艳的蓝色帽子，白袜子和亮皮鞋与她脖子上那条优美的,蓝宝石项链有些不协调,这是由于那场春雨我送给她的礼物。

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