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 Hua