class 具体点，指某一节或多节课课例如？ I took classes in Indian music.
我参加了印度音乐课程的学习。 science： 更高一点层面的，或者说概括的某种学科a particular area of this. 专门科学
veterinary science.兽医学。
the agricultural sciences.农业科学。 subject:更多用来指具体的某门课程 a branch of knowledge studied or taught in...
