Not just studying for mandatory courses, but subjects you seek out only to learn.

不只是为了学习必修的课程，而是要找科目来学。

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For the last few years, university students have been given the chance to choose a few optional courses in additon to the mandatory courses of their majors.

最近几年来，除了上专业必修课之外，大学生们还有机会选学一些选修课。

youdao

The courses will be optional at first, but could become mandatory.

首先这些课程是可选课程，但是可能成为强制性的。

youdao

Sure, we could treat car salesmen like securities analysts and have them attend mandatory ethics courses whenever they step out of line.

FORBES: Ralph's Used Car Analysts