I would say: "It's red."

我如果说：“那是红的。”

youdao

A red block. So here it is. It's red.

它是红色的。

youdao

why not make any chance of people not realizing that it's red?

为什么不利用,人们并未意识到那是朵红玫瑰这点？

youdao

" It's actually really orangish more than it's red and it's also kind of brown too.

VOA: special.2010.07.28

One example of a very different cell is a red cell or red blood cell, these are the cells that give blood it's red color.

举个高度分化细胞的例子,红细胞,或称血红细胞,它们赋予了血液鲜红的色彩

耶鲁公开课 - 生物医学工程探索课程节选

I mean it's understandable-- this was before 1879 which was when Red Cliff was founded, and long before Harvard became co-ed.

这是可以理解的-,那是1879年之前，雷德克利夫学院还没成立，远在哈佛成为男女合校之前。

哈佛公开课 - 幸福课课程节选

What gets our goat is if we're sitting at a red light for no reason other than that it's red.

BBC: Viewpoint: Is it time to get rid of traffic lights?

My face is the most prominent thing about me: it's red, and sometimes it looks healthy and windburned and full of what you might call life, and sometimes it just looks enflamed.

NPR: Chapter 1

It's red hot and rolling now.

NPR: S.C. Activists Weigh In on Obama-Clinton Race Rift