Ppf
[医][=pellagra preventive factor]抗糙皮病因子，维生素pp
🗣️ 情景例句
How many stamps do I need?
我需要多少邮票？
He who cannot hold his peace will never live at ease.
嘴巴不紧，生活不宁。
for the descriptions given by people who claimed to have seen the puma were extraordinarily similar.
因为凡是声称见到过美洲狮的人们所描述的情况竟是出奇地相似。