此题要求改正所给短文中的10处错误。请在右边横线上写出改正后的词。包括：多词，缺词和错词。
Dear Editor,
Recently, my classmates have had a heated discussion about that
we should have optional courses in high schools. Some students were
in favor of optional courses. They say interest is best teacher
and our spare time will be colorful and meaningful. Students
can not only enlarge their knowledges but also improve their abilities.
However, others are against the idea, said that optional courses
will take up too much time as well as energy. In addition to, some optional
courses have something to do with the College Entrance Examination. They
are afraid they’ll fall behind their classmates if they will take the
optional courses. I’d like to take one or two of the optional courses, which, I think, will certain benefit me a lot.
Yours truly,
Li Huathat→whether
网友回答
(答案→)that→whether
解析：
【小题1】后面的宾语从句讨论的是不确定的事实，用whether.
【小题2】本文的基本时态是现在时。
【小题3】形容词最高级前面加定冠词the.
【小题4】上下文可知是指他们的时间是多姿多彩的。
【小题5】知识是不可数名词。
【小题6】分词在句中作状语。Other与say构成主动关系，使用现在分词。
【小题7】In addition单独使用表示：另外。
【小题8】根据上下文可知这些选修课与高考关系不大。
【小题9】条件句中用一般现在时代替将来时。
【小题10】副词修饰动词。