That's how it is on their official website. Am I right in saying that they are not native English speakers? 知乎，让每一次点击都充满意义 —— 欢迎来到知乎，发现问题背后的世界。 Actually, they keep using these two words just like this all the time. In one and the same Lyrics they use "at a lesson" and "rein class" https://youtu.be/T0zWXvhEQwo?si=wNc6ihu97ShtIl7u