Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
Is he still in his office?
他还在办公室吗？
Nothing so necessary for travellers as languages.
旅行者最需要的是几种语言。
The farm was owned by two brothers, Joe and Bob Cox.
恩得利农场属于乔。考科斯和鲍勃。考科斯兄弟俩所有。