增加：在缺词处加一个漏字符号（∧），并在此符号下面写出该加的词。

删除：把多余的词用斜线（＼）划掉。

修改：在错的词下划一横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均仅限一词；

2）只允许修改10处，多者（从第11处起）不计分。

    As to the online course, it is extreme convenient and flexible in time to learn from something. However, there are many different courses who are from different teachers or institutions. You can learn them over or again. Then there're social forums where you can communicate with other learners, helped to improve your understanding.

    But on the other hand, you can't see and feel teachers as in traditional classes. You will also fail to enjoy the liveliness in it. And a great quantity of problem will not get solved in no time when meet them. So you can try the online course, and you can also learn in the school in the same time.