Sulfenamide
亚磺酰胺
🗣️ 情景例句
Is this your very first advanced aerobics class?
这是你第一次上有氧运动高级班吗？
All things are difficult before they are easy.
凡事必先难后易。
It was my first flight. I was nervous when the plane took off.
我第一次坐飞机，起飞时我有点紧张。