The psychologists reasoned that if the children knew what they usually looked like, they would be surprised by the unusual red mark and would start touching it.

心理学家推断，如果孩子们知道自己平时的样子，他们就会对这个不寻常的红色标记感到惊讶，并开始触摸它。

youdao

The editor will mark the validation errors with red marks on the left and right sides, and add a red wavy underline to the invalid syntax.

编辑器会左右两侧用红色标记标明验证错误，并给无效的语法加一条红色波浪型的下划线。

youdao

There was a red mark on his back in the shape of the letter S.

他的背上有一个蛇形的红斑。

《新英汉大辞典》

This past week,volunteers from Red Cross and Red Crescent societies around the world gathered in Solferino to mark the anniversary.

VOA: special.2009.07.01

but I mark the whole paper up with a lot of red ink if there are mistakes,

但我在批论文的时候，也会把语法错误的地方用红笔标出来，

与哲学系教授 - SpeakingMax英语口语达人

But when she turned pale, there was the mark, like a red stain upon snow.

VOA: special.2009.09.26

The teacher tried to get it off with a wash cloth, and it left a red mark on the side of his face.

CNN: What teachers really want to tell parents

Helping one blond girl wash her hands, she notes in alarm a bright red mark on her face, what appears to be a fresh injury.

FORBES: Child Care Director Is Also Diaper-Changer in Chief

"I've been bitten so much I'm used to it, " said Leung, rolling up the sleeve of his oversized blue fleece jacket to reveal a red mark on his hand.

NPR: Hong Kong Poor Living In Cages And Cubicles