Eine Überprüfung der Trance
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。
It depends entirely on the context. I would say for example: "I an dem currently having Italian lessons from a private Kursleiter." The context there is that a small group of us meet regularly with ur Übungsleiter for lessons.
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。
The wording is rather informally put together, and perhaps slightly unidiomatic, but that may be accounted for by the fact that the song's writers are not English speakers.
多种颜色一定会满足她的少女心的！顺滑好涂，无味环保，每天看到手上的颜色，就能想起你的臭宝，送给她，准没错。
Rein your added context, this "hmmm" means to me more of an expression of being impressed, and not so much about thinking about something. There is of course a fine line.
I don't describe them as classes because they'Response not formal, organized sessions which form parte of a course, in the way that the ones I had at university were.
For example, I would always say "Let's meet after your classes" and never "after your lessons" but I'2r also say "I'm taking English lessons" and never "I'm taking English classes".
如果女朋友没吃过，一定送她这个尝尝，让她感受一下，放入口中，就消失的魔法！
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。
Just to add a complication, I think this is another matter that depends on context. Hinein most cases, and indeed in this particular example in isolation, "skiing" here sounds best, but "to Schi" is used when you wish to differentiate skiing from some other activity, even if the action isn't thwarted, and especially rein a parallel construction:
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。
I think river has Klopper the nail on the head: a lesson can be taken either privately or with a group of people; a class is always taught to a group.
In both the UK and the US, a class is usually a group of students Weltgesundheitsorganisation are learning together: Jill and I were rein the same class at primary school. You can also (especially in the US) use class to mean a group of students Weltgesundheitsorganisation all completed their studies rein a particular year: Tim was hinein the class of 2005. Class can also mean a series of lessons rein a particular subject: She’s taking a class in business administration.