他在考试前做了些预备性的复习。

He did some ___preparatory revision before the exam.

这些预备课程帮助学生为大学学习做好准备。

These ___preparatory courses help students get ready for college studies.

她在进入大学前参加了一年的预备课程。

She took a one-year ___preparatory course before starting college.