Sigma.
[医] 千分之一秒
🗣️ 情景例句
A young male may be addressed as 'young man'.
一个年轻的男性可以被称作 'young man' 。
Do not cut down the tree that gives you shade.
不要忘恩负义。
I really ought to go and have my eyes tested.
我确实该去检查一下我的眼睛了。