Sffd
abbr. step-function frequency discriminator 阶跃函数鉴频器
🗣️ 情景例句
Well, he wakes up several times during the night,
噢， 他一夜醒了好几次，
She began playing the violin when she was nine.
她从九岁就开始练习小提琴。
I respect your work.
我对你的工作表示敬意。