快刀不磨黄锈起。

Knives get rusty when not sharpened.

youdao

在食堂自觉排队的学生越来越多，不遵守黄线规则的学生越来越少。

More and More students stand in line consciously in the cafeteria. Less and Less students disrespect the Yellow line.

youdao

黄师父：为什么不印多一百份呢？ 我想今年晚些时候我们还用得上。

Master Huang: Hmm, in fact, why not a hundred more? I'm sure we'll need them later this year, anyway.

youdao

You don't see a red and yellow, you don't see green and blue.

你们不可能看到红连接黄 或者绿连接蓝

耶鲁公开课 - 生物医学工程探索课程节选