假定英语课上老师要求同桌之间交换修改作文，请你修改你同桌写的以下短文。短文中共有10处错误，每句中最多有两处。错误涉及一个单词的增加、删除或修改。

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：每处错误及其修改均仅限一词

    On Wednesday of this Culture & Art Week, we invite the American teacher Prof. Hudson to our school. He gave a class to us and his class left us a very deeper impression.

    Prof. Hudson had a free talk with us in the simple but humorous English. He spoke slowly and clearly so that we could follow her well. In the same time, he would repeat that we did not understand.

Greatly encouraging, most of us took an active part his class.

    From his lessons, we came to the conclusion that it is not so difficult to learning English well.

如图Ⅰ和Ⅱ分别表示某种病毒先后两次侵染人体后，人体产生抗体的数量变化曲线，相关叙述错误的是（  ）