Sffd
abbr. step-function frequency discriminator 阶跃函数鉴频器
🗣️ 情景例句
Help me with this tie, will you?
帮我打领带 好吗
When did you buy the car?
你什么时候买的车？
Antique shops exert a peculiar fascination on a great many people.
古玩店对许多人来说有一种特殊的魅力。