Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
I need multimedia capability for my system.
我的计算机系统需要多媒体功能。
It's nothing special.
这没什么稀奇。
It was simply a blank sheet of paper.
而是一张白纸。