[大学](https://eikaiwa.dmm.com/uknow/questions/36222/)の受験生はpreparatory studentで大丈夫です。また"student preparing for an exam" でもオッケです。
受験生をexamineeやcandidateと言います。
ご参考になれば幸いです。
Exam candidate is a person taking an examination or test. In this case the entrance exam for the college.
For example: "I am an exam candidate for the college entrance exam so that I can be a prospective student".
Prospective student are students who might attend a school in the future
Exam candidate（試験候補者）は、試験またはテストを受ける人のことです。
この場合、大学の入学試験を意味します。
例）
"I am an exam candidate for the college entrance exam so that I can be a prospective student"
「私は大学入試の試験の受験者であり、将来の学生になる可能性がある」
Prospective student(将来の学生）は将来の学校に通う可能性がある生徒です。
Since this student is aspiring to become a student at the university or college, you may call him/her a prospective student or an aspiring student. However, since he/she is currently studying for the entrance examination and will be admitted to the university or college only after he/she has passed the entrance examination, you may, presently call him/her:
Prospective student.
or
University entrance examinee.
or
University entrance examinee.
All test takers should report to the room for their entrance exams.
Exam students are very busy preparing for their entrance examinations.
All exam students may now begin their entrance exams. You have one hour.
受験生 test taker, exam student
すべての受験者は入室試験のために部屋に報告する必要があります。
All test takers should report to the room for their entrance exams.
受験生は入学試験の準備で非常に忙しいです。
Exam students are very busy preparing for their entrance examinations.
すべての受験生が入学試験を開始できます。 １時間あります。
All exam students may now begin their entrance exams. You have one hour.
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