Smiling is apparently a universal sign of friendliness and approval.

微笑显然是友好和认可的普遍标志。

youdao

Baring the teeth in a hostile way, as noted by Charles Darwin in the nineteenth century, may be a universal sign of anger.

正如查尔斯达尔文在19世纪指出的那样，怀有敌意地露出牙齿可能是人们表现愤怒情绪的通用表情。

youdao

Crying is a nearly universal sign of grief, though some mourners report that, despite genuine sorrow, they cannot shed tears—sometimes even for years after their loved one has gone.

哭泣几乎是悲伤的普遍标志，但一些哀悼者表示，尽管他们确实感到悲伤，却流不出眼泪——有时甚至在他们所爱的人去世多年之后也是如此。

youdao

"I was choking on a brat and I gave the universal sign to Kaiden that I was choking."

VOA: standard.2010.02.23

It's a good thing Nathan Gelder knew the universal sign for choking when he was having lunch last year with his friend Kaiden Condos.

VOA: standard.2010.02.23

Current smartphone technology allows for nearly infinitely granular targeting based on behavior, third-party data, contextual data such as location, and universal sign-in profiles.

FORBES: Google Glasses And Other Prescriptions for Consumer Engagement