Pfu
空斑形成单位; 疱斑形成单位
🗣️ 情景例句
I was teaching music,
我当时教音乐，
Perseverance is vital to success.
不屈不挠是成功之本。
This is because the surface of the earth is not flat but round.
因为地球表面不是平的，而是圆的。