大学时我上了不少写作课，但是最有用的还是商务写作课。

I took many writing classes in college but perhaps the most useful was one focused on business writing.

youdao

我读大学的时候有一门商务写作课，无疑是我上过最实用的课程，因为它有一整个章节都在教电子邮件规范。

There was a course offered at my university on business writing that I have heard was the hands-down most useful course ever taken because of a whole section on email etiquette.

youdao