elective/optional course： 選修課
Optional Elective Course： 任意選修課
例：
This course is a specialized optional course for overseas undergraduates who major in Chinese.
本課程是為漢語言專業本科的外國留學生開設的壹門專業選修課。
Is that optional course as hard as everybody says?
那個選修課真的就像每個人說的那樣難嗎?
In college, English is a required course and psychology is an elective course.
在大學裏，英語是必修課而心理學是選修課。
This is a elective course based on the study of the thoughts of Marx on historiography.
“馬克思史學思想研究”是根據作者多年精心研究而設計的壹門選修課程。