Coboundary operator
[计] 边缘算子
🧩 词语组成解析
[计] 上边缘
🗣️ 情景例句
And don't ever forget it.
永远别忘记这一点。
You forgot to fasten the collar buttons.
你忘了系鞋带。
It's about a time when there were black slaves in North America. It's about their fight for freedom.
（它）讲的是有一段时期，北美洲存在黑奴。影片讲述他们为自由而斗争的情况。