Semigroup
[计] 半群
🗣️ 情景例句
Don't worry about it. It's nothing.
别担心，没事儿。
It is too late to lock the stable door when the steed is stolen.
贼出关门。
Though the sound could be heard clearly, it took me a long time to react.
虽然声音听得很清楚，但我过了好一会儿才作出反应。