Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
Blue is for boys, and pink is for girls.
蓝色是男孩子的 ，粉红色是女孩子的。
How many gallons are you going to take?
你要拿几加仑？
I suppose it's better to be safe than sick.
我想安全总要比生病好。