Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
I've been doing this job for 25 years, and I tell you you're going to stuff it up doing things this way.
我干了这工作已有25年了，告诉你，你这样做事情，会把事情办糟的。
Fortune is fickle.
天有不测风云，人有旦夕祸福。
Which speech are you going to?
你打算去听哪个报告呢？