Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
What does he say?
他说了些什么？
Love makes the world go round.
爱能感动世界。
But wouldn't you like to spend an extra day or two here?
你们不愿意在北京多待一天吗？