Sffd
abbr. step-function frequency discriminator 阶跃函数鉴频器
🗣️ 情景例句
on the farm.
在农场。
We invited two guests to dinner,but they didn't come.
我们邀请了2个客人去吃晚饭，但是他们没来。
My watch is faster than yours.
我的表比你的表快。