class 从“班级”引申指学生在一起上课，还可表示“(一节)课”。
lesson 主要指教材中的一课或每次授课的单位时间。
lecture 指讲课。
course 指在一段时间内教完或学完的完整的课程。
参考例句
1. The deer coursed the open field. 这只鹿奔跑越过开阔的原野。
2. Of course, I know what that means. 当然了，我知道那意味着什么。
3. The ultimate test, of course, is jokes. 当然，极限试验仅是一个玩笑。
英英解释
n.
1. education imparted in a series of lessons or meetings
2. a connected series of events or actions or developments
3. facility consisting of a circumscribed area of land or water laid out for a sport
4. a mode of action
5. a line or route along which something travels or moves
6. general line of orientation
7. part of a meal served at one time
8. (construction) a layer of masonry v.
1. move swiftly through or over
2. move along, of liquids
3. hunt with hounds adv.
1. as might be expected
