Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
I'm really sorry to hear about that.
听到这个消息真让我感到难过。
The falling out of lovers is the renewing of love.
情人越吵越亲密。
He walks with a quick pace.
他快步走路。