Sigma.
[医] 千分之一秒
🗣️ 情景例句
The smog in L.A. is caused by air pollution and water vapor.
洛杉矶的烟雾是由空气污染和水蒸气造成的。
Have you somewhat to do tomorrow,do it today.
明天如有事，今天就去做。
Like this?
像这样？